KASH-GREENIVICH RAINFALL, 1515-1903 291

MONTHLY RAINFALL AT T H E ROYAL OBSERVATORY, GREENWICH, 1815-1 003.

BY WILLIAM CARPENTER NASH, late of the Roynl Observatory, Greenwich.

[Read May 18, 19041.

Ix iindertakiiig the onerous task of drawing up an authoritative table of rainfall for the long period embraced in the observatory series, i t appeared necessary a t the outset to inquire fully into the circumstances relating to the early history of the register. For several years prior to the establishment of the regular meteorological service a t the Royal Observatory in 1841, a Meteorological Journal had been kept there (unofficially) by A h . Belville and other members of the staff: This Journal practically begins in the year 1511, but i t was not until December 18 I4 that rainfall began to bc observed. No information is given in the Journal with regard to the position of the gauge, which is incidentally referred to here and there in the register as “ Troughton’s.” Its position, however, appears to be defined by the following statement prefixed by the Astronomer-Royal (the late Sir George Airy) to a manuscript table of rainfall from 1515 to 1560, preserved in the Iioyal Observatory records : “To 1833 or thwecibouts the rain-gauge was in the front Court, on a small plot of grass near the N.E. Dome ; from that time to 1840 on thc leads of the Library.’ The readings since 1840 are those of raingauges on the ground in the hIagnetic Grounds.”

The observations were made a t first with considerable regularity, but after Mr. Belville had changed his residence from the Observatory to the town of Greenwich in 1822, they were made less regularly, as his attention seems to have been engrossed by his own private journal a t Park Row. It does not appear, however, that Mr. Belville considered the Observatory journal as in any sense an official document, and in the Relville Journals (now the property of the Royal Meteorological Society) the Observatory observations made by him are included. Although the Observatory journal was partly in abeyance from 1822 to 1526 it would appear that the rain- gauge was never removed from the Observatory, and that the references to rainfall in the Belville Journals are entirely based upon Observatory records until 1828, when Mr. Belville commenced an independent series of rainfall observations a t his private residence (then Park Terrace, Green- wich), After 1830 the observations for the journal at the Observatory were mainly made by Mr. Rogerson.’

I n 154 1, upon the establishment of the Meteorological Department under the conduct of Mr. Glaisher, a Crosley self-registering gauge was mounted in the grounds in January for daily observation, followed in February by an eight-inch cylindergauge of the ordinary construction for monthly measurement. The original six-inch “ Troughton ” gauge was retained in its position on the roof of the Library, a t the height of

1 22 feet above the ground. 2 It is interesting to note that Mr. Rogersou ako kept a private journal from 1534 to

1853 at his residence at Croonis Hill, Greenwich, and that his observations were printed monthly in the .\-a titical Magaziiie.

292 N A S H 4 H E E N W I C H RAINFALL, 1815-1903

33 feet above the ground, and other gauges were also introduced a t greater elevations. The monthly gauge continued to be the standard for reference until March 1861, when another gauge of similar construction and dimen- sions was mounted by its side, to be used for daily observation. [The introduction at this time of graduated measuring glasses marked a con- siderable advance in accuracy of measurement.] At the beginning of 1899, on account of the extension of the Observatory buildings, the standard gauge was shifted to a more exposed situation 400 yards east of its former position, check-gauges being retained in the Observatory grounds.

The monthly values given ill Table I. are based upon the records given by the gauges specified in the foregoing statements, attention being given to the following notes relating to necessary corrections, etc. 1840. February.-“ 0.60 in.” marlwl “ uncertain ” in journal, the gauge

1820. h1arch.-No record. “ 1.50 in.” adopted by Mr. Glaisher. 1834.

proving defective.

June 11.-“An accident to the gauge prevented its [‘record’] being carefully ascertained.” Monthly amount taken as entered.

December.-Only one entry (0.0s in.), but in the weatlirr nvtcs several entries r e l d n g to snow appear between December 1 3 and 29. On BSth, snow noted “ 3 iriches deep.” Next rain entry in journal is on Janunry 7, 1830, “0-65 in.” noted as “ in part melted snow.” I t is considered that three-fifths of this ntnount should belong to the December fall, and the record has therefore been increased by ‘cO.10 in.” The Cobhum record is 0.42 in.

November.-hin left in gauge and measured with December amount. Divided proportionally by reference to Belville’s record.

183% February.-Left till end of March : divided proportionally hy reference to Belville’s record.

1832 to 1840 (inclusive).-All records considered to have been made a t the height of S? feet above the ground: reduced to ground level using the proportion established by comparative records made between 1841-1850. [1838 included on the authority of Belville’s record.]

August.-Left till end of September : divided proportionally by reference to the record given by another gauge.

1829.

1831.

The corrected values are printed in italics. 1855.

NISH-GREENWICH RAIPJFALTJ, 1815-1003 293

TABLE L-NONTIILY RAISFALL A r THE KOYAI. OI:SEI~YATORY, CBEKNWICII, FROM 1815 TO 1903.

j k EARS. 1 Jan. I --

in. I 1815 .7S 181b 1.90 1817 2.85

1819 2 .12 1520 1.73

1818 1.73

' IS21

1825 1826 1S27 182s is29 1830

I S46 1847 I S48 IS49 I 850

1851 is52 1853 18-54 I855 1856 1857 185s 1859 I 860

1861 1862 1863 I 864 1865 I 866

242 240 2.82 1.38

I .50

2.70 3.60

I .40 1.47 2.63 2.60

.75

.80 1.81

a 5 5 1.79 271 4 8

3.32 3.68

I .20

I .20

2.1 I

~

~

Feb.

in.

1.47 1.19 1.S9 2.67 .60

.04 9 s

3'17 2.34 .86

I .66 .60

I .04 1.17 2.28

244 .37 4' 00

.44 2.89

1.83 -..r9 1.70 r '3'

1-32 1-05 2'39 2.32 *93

I 4 7 1.39 2.60 2.30 I .40

1.25

9 I .48

1.20

2.00

1.21 I .00 1.10

.20 1.70 236

1.10

1.80 4 6

*76 1.75 4.03

Mar.

in.

1.71 1.90 3.45 1.53

, I .50

3.45 1.39 I .36 I 6 9 1.30 1.66 2.40 .S6 .60 .2S

2.03

1.03 4 9 260 "117 55

1.09 1.94 170

1.35 1.90 *5 I

2.30 1.51

.77 3. I 0 .60 .40

4 0 5 . I 7

1.50

.32 I .98

4 3 .80

1.35 1.86

2.15

3.54 .70

2.53 .85

I .63

-

2.00

1.22

.sa

1.10

.\pril,

in. 2 4 7 I .94 .06

2.99 2.82 I .48

1.82 2.56 1.75 1.89 1.75 .97

1.16 2.17 4.35 2.54

1.55 .40

r.;r 2-0

r.04 2.71 1.21

5s f .44 .ro

1.92 .43

1.72 $35 .55

3.05 .99 344 1.98 2.25

2.30 .49

3.21 .59 .09

2.28 I .40 2.25 2.17

-

I .oo

4 3 2.82

-45 4 2

'40 2.44

May.

in. 2.14

I .95 4.12 2 . 5 j 2.9s 3.57

I .90 .74

3'77 2.97 2.47 2.39 1.47 '45

1.96

1.52

'55 .'?5 '97 3'00 r.32 99

1.50 1.66 2.03

2.06 2.09 3.75 .30

I .50 1.40 *40

3.70 2.30

.so 1'90 1.50 3.5' I .80 3.45 .33

2.35 3.90

1.79 2.84 1.25

4.37 1.94

-

2.22

2.21

2.00

2.00

July.

in. 1.57 3.91 3.86 439

4 3 s

-

2.00

2 4 2 4.07 3-30 1.81

. I 0 2 . a 1.25

3.7b 1.69

3.09 .70

1.65 5.3' .-as

r.70 r.56 1.97s 7' 7' 1.63

3.60 2.96 2.42 2.1s 1.85 I .50 .67

1.98 2.90 2.82

4 2 0 2.25 5.48 1.75 5.25

.90

3'00 3.30 2.80

6.4:

1.10

2 2 0 1.66 .88 .27

2.27 1.62

Aug.

in. I .s; 2.30

2.53 .07 .36

1.70

1.92 1.81 2.68 3.95 2.48 I .69 1.05 3.75 4.33 3.55

1.77 3.44 r.7r 3' 27

a 63 4.j2

2.7r, r.oJ

-

1.10

f .Of

2.20 1.78 3.62 1.71 3.10 400 1.95 4 2 5

.45 1.70

2.60 4.35 2.75 2.61 I .40 2.42 2.50 1.50 1.13 3.68

.57 3.01 1.82 1.31 3.97 2.42

-~ bapt. Oct.

in. ~ in. 1.07 ~ 2 39 1.96 2.61

4 1 2.39 3.78 1.89 3.13 2 1 3 2.23 2.64

3.40 2.42 1.37 3.60 4 9 , 3.96

2.56 2.69

--

j . 2 1 I2.44

3.27 3.24

1.97 4J

1.98 37

4' 15 313 r Q,- 2.99 4.95 2 94

395 3.99 .46

1.19

1.79 I .56 2.38 3.25 1.35

'50 3 80

*9 1.95 2.80

3'40 46

3% 3.10

1.46 1.61 2.95 2.76 .16

3'90

2 1 2

1.41 I .67 .66

1.97 2.49 I '29 '47 p.20 p"7 2.46 r.99 r.90 1.62

5.95 1.41 1.25 1.01 1.38 5.13

? 50 2.70 1.58

2.18 3.75 4.23 2.42 5.20 1.91 Q.20

I -44 3 60 1.60

*88 4.07 1.82 I .06 5'90 2.09

2.00

Nov.

in. 1.37 2.74 1.80 2.49 2.69 1.76

4.33 3.66 1.55 j .8S 2.85 2.46 1.17 .85

1.32 3.09

1.45 14'7 1.60 I '50 ' 3 7 a67 1.85 3'50 494 3.16

3.70 4.25 2.30 4.50 2.40 1.52

1.50 2.1s

.65 6.00 1.95 1 9 1.50 1.25

1.35 .SO

2.90 2.50

5.07

1.59 2.57 2.39 I .48

-

2 a o I .20

1.00

Dec:

in. 2.05 2.82 353 1.34 3.48 1.57

4.72 2.26 2.48 3.55 2.92 1.28

3.33 2'33

.48

2.3 I 1.19 485 r.22 9

"43 1.90 a66 50

240 .74 '40

-

1.20

2.00

.36

1.13

2.55 2.40 1.35

.55

.80 1.41

1.83 .55

1.70 2.17 2-75

1.25

1'59 I .08

1.85

2 0 3

2.00

2.20

1.10

3; __

Yearly rotais.

in. 20.52

27.40 26.58 2345 28.24 25.27

31.53 24.95 2438 32.98 22.25 20.7 I 22.38 28.44 23434 24.22

26.41 18.26 2384 10.08 25.45 "7 84 zr.71 "459 30.78 18.67

3326 22,57 2447 23.20 22.34 25.29 17.61 30.10 23.58 19.53

23.53 34.01 29.99 I 9.0 I 23.59 23.27 21.16 17.70 25.83 31-90

20.45 26.32 I 19.66 i 16.38 28.70 I

-

30.72 ' I

-\

291

Yearly Totals.

-- in.

28.46 25.15 24.02 18.55

NASH-GREENWICH RAINFALL, 1815-1003

iIION'I.IILY RAINFAI.L hl' TFIE ROYAL OBRF.I:VATOI:I.-CCO)ltinUFd.

1.37 1 *57 ~ 1.23 434 2.92 407 2.55 ~ 258 .31 3.58 , 1.85 1.69 4 1 3 12.90 , 1.06 1.61 1 3 0 6 15.76 1.78 3.53 1.76 1.66 3.45 1.16 .76 ~ .91 1 .65

7.65 2.06 3.00 I

EARS

22.30 30.02 23.36 1995 27.97 2410 27.28 28.95 31.36 29.68

Jan.

.19 2.71 2.27 2.49

.82 1.59 2.55 , .83

.oq 1.04 .99 2.54 2.83 1.13 3.02 3.60

.41 5.42 2.20 1.77

3.77 11.47

April.

25.72

21.91 18.05 2400 24.21

25.18

19S6

June. July. --

2.67 1.14 2.19

j.00 2.14 2.23 1.46 2.28

3.03 1.50 1.27

1.95 2.51

Aug.

25.04 22.31 20.12 26.89 19.73 22.42 22.13 18.85 22.33 22.31

20.29 I934 35.54

Sept. Oct. ~ Nov. Dec.

1.62 .93

3.00

Fsb. ' hIar. --

I 867 1868 I 869 1870

1871 1872 1873 IS74 1875 1876 1877 1875 1'379 I sso I881 I882 I 883 I 884

I 886 I 857 1888 I 889 I 890

1891 1892 1893 1894 1895 I 896 1897 I 898 1899 [goo

I885

in. 2.79 4.19 2.92 1.49

2.05 3.63 2.45

2.99

4.35 4 7

2'59 *26

1.66 1.35 I .69 1.77 I .42 368 1.15 4 9 .84

2.0s

I .56 .38

"45 3'09 I .62 .64

.65 2'53 2.2s

I .00

1.1 I

I .h2

in. 2.28 I .07 1.41 2.05

2.13 1.33 '45 .56

2.32 2.23 I .06 .60 .60

1.83 1.14 .75

1.37 1.50 1.14 1'35 2.7s 1.32 1.96

2.14 1.09 .43 .73

1.43 3.00 335 1.40 .61 .92

2.17 1.36

I .52

1.10

2.20 -

in. 2.34 1.67 343 .47

.68 3.09 I .49 .42

I .46 1.13 1.38 429 3.36

.SO

1.61 1.37 1.71 .96

423 1.73

3.30 1'34

2.69 1.66 .53

1.52 '4 5 '27

1.25 2.64 1.65 1.37

2.11

*65

in. 5.81 1.06 3 5

3.25 2.36 I .85 2.59 5.28 .67

2.46 .3 1

3.72 3.8 I

2.14 2.45

1.77 ' 5 0

2.51 1.29 6.75 2.06 4.50

3.39 1.53 3.33 326 3.39 I .06 -73

"34 1'74 1.41

1.72 I '09 5.27

2.01

2.00

in. 2.64 2.61 1.21 2.02

4 6 2.70 3.18 1 4 4 2.28

2.90 5.38 5.19 .98

3.89 1.16 .7 1 .67

I .32

2.35 3.73 1.81 2.54

3'72 3.03 1.25 303 2.14 2.06 2.86 *86 .3 5 2.03

2.03 2.93 4.82

2.01

1.12

in.

1.28 2'34 '54

I .09 .77

1.93 *94 4 2

1.50 1.71

382 2.36

2.45 1.15 2.89 1.50 2'33 3 6 .53 .89

2.19 I .04

.OS I .69 2.72 1.59

.36 2.38 1.19 1'93 3.55

.87

.79 1'37

1.52

1.22

1.10

.22

-

in. 1.77 .47

1.15 .39

2.95 I .64 2.56 2.42 2.28 I .os .68

4.57 429 2.26

1.86 2.36 1'34 2.24 1.67 '44

1.23 3.36 2.07 2.54

.96 227 .82

2.04

1.94 1.93 1.75 .76

2.81

1.49 3.10 6.07

1.97

.21

-

412 1.39 2.52

2.66 2.58 1.15

4 2 2.87 4.00

2.22

1.24 1.41 2.21 1.03 .73 1.30

1.69 3.93 .65 1.19

4 2 432 2.01 3'88 1.29 416 1.25 3.99 .93 2.69

5.54 2.80 2.70 .48 . jo 3.15

2.23 2.34 1.14 1.55

1.65 1.24 2.24 444

2.25 2.72

1.35 2.60

--

1.45

2.00 2.2 I 1.83 3c€J 2.89 1.19 I .07 2.4 I 3.73

.67 1.29 1'93

2.02

1.61 1.95 2.45 2.33

The values given for the years 1867 and 1868 in the foregoing table are those printed in the Greenwich Volumes, and are the values usually received and adopted. But by comparison with the records given by neighbouring gauges, and also with those obtained at Camden Square, i t would seem that several of the monthly values are too large, and that the values given by the adjacent monthly gauge are more reliable. The following are the values given by the monthly gauge in those years :-

Years. Jan. Feb. Mar. April. May.

_ _ ~ ~ _ _ _ _

NASH-GREENWICH RAINFALL, 1915-1903 295

If these numbers were used instead of those already given, the averages a t the foot of the tablo would be diminished by .01 in. in each of the months April, June, July, September, November, and December, and for the year by .OG in. It is probable, however, that i t may be considered desirable (as the effect produced is somewhat small) not to alter these numbers, but simply to draw attention to the discrepancy.

In Table 11. the annual values of the rainfall are given, and the percentages of the average amount, which could not be conveniently included in Table I. In addition, the rainy days are also given for as many yeiirs as h i l y observations were completely made, but in several cases the values for some of the e : d y years are subject to suspicion.

~~ ~ _ _ Rainy Days ~

lhinfnll. 1 Rainy Days. Rainfnll. i Rainy Days. ~

Y - . 22; 6 5 1 ? ;2 Ccd -

% 99

124 I 24 90 94 78

95 77 74 89

-

...

...

...

...

...

...

...

...

...

...

...

...

...

...

...

...

I I 2 88 99 90

~

~~

- i % -

156 I95 I95 142

148 123

I49

I 16 140

121

...

...

...

...

...

...

...

...

...

...

...

...

...

...

...

...

,76 : 38 ; 56 :42

~-

Sears. ~

, E -t

C

0

Years I Yunrr

1 I

1815 1816

' 1817 I818 1819 I820

IS21 I 8 2 2 1823 1824 1825 1826 1827 1828 1829 1830

1831 I832 1833 1834 1835

1837

1839

1836

1838

I 840

1841 1842 1843 1844

% 109 100 I00 I 36 97 90

s 9 97

117 92 91 92 77 71 92 I21

93 107 85 74 93

103 91 93 82

10;

125 91 88

I I 0

IS75 I S76 1877 IS78 1879 I 8Sa

1881 I882 I 883 I 884 ISSS 1886 1887 I 888 1889 I 890

1891 I 892 1893 I894 1895 I 896 I897 1898 I999 1900

1901 I 902 1903

1846 I 25.29 1847 i 17.61 ISJS jo.10

23.58 I 9 5 3

2S.9S' I19 31.36 129 29.68 122

25.72 106 25.18 103 21.91 go

24.00 99 24.21 99 1986 82 27.jr 1 1 3 ~ 3 . ~ 8 96 21.86 90

25.04 103 22.31 92 20.12 83 26.89 I 10

22.42 92 22.13 91 18.85 77 22.33 92 22.31 92

20.29 83 19.34 79 35.54 146

18.05 74

19.73 81

18 i9

1852

1853 1854 1855 1S56

rSSa

rS51

::::: 2 1861 1862 1863 1864 I 865 I 866 I 867 I 868 I 869 1870

1871 1872 I873 1874

~~ ~

23.53 34.01 2999 1 9 0 1

23.59 23.27 21.16 17.70 2 5 4 3 31.90

20.45 26.32 19.66 16.38 28.70 30.72 28.461

24.02 25.151

15.55

22.30 30.02 23.36 1995

97 140 123 76 97 96 87 73

I 06 131

84 I08 81 67

I IS I 26 117 103 99 76

92 123 96 82

~

24.361 ... Average

The rainfall average is based upon the observations for the 89 years. 1815.1903 : and that for the rainy dayr upun the results for the 63 years, 19+1-1go3.

I . A R ( : E A N N U A L FALLS (exceeding 20 in.).

in. Year. Amount. No. of h i n y Dnys.

1821 31'53 149 1 1824 32.98 140 1 1839 30.78 ... 1841 33'26 176 1848 30.10 214 1852 34'01 152 1853 2999 184 1860 31.90 191 1866 30.72 173 1872 30.02 197 18i9 31'36 185 1880 29.68 160 1903 36'54 179

SMALL ANNUAL FALLS (less tlinn 20 in.).

in. Year. Amount. No. of Rainy Day%

1832 19.26 ... 1840 18.67 . . . 1847 17'61 157 1850 19.53 141 1854 19'01 145 1858 1770 112 1863 19.66 131 1864 1 6 3 8 116 1870 18.55 129 1874 19'95 139 1884 18'05 160 1887 19.86 143 1895 19.73 158 1898 18.85 142

NBSH--GREEN\VICH RAINFALL, 1815-190:3 29 7

The monthly values will now be considered. In Table IV. a summary is given of the monthly averages and extremes of rainfall and rainy days.

1880, October . . 7.65 on 18 days

1828, July . . . 6.13 ,, ( 1 ) ,, 1903, Jime . . . 6.07 ,, 10 ,, 1852, November . 6.00 ,, 22 ,, 1811, October . . 5.95 ,, 22 ,,

1888, July . . . & i 5 ,, 26 ,,

hIosrtr5.

January . February . Alarch. . April . .

N a y . .

Jiine . . July . . .August. . Septentber October . November

1865, October . . 5.90 on 19 clays

1860, June . . . 5.80 ,, 23 ,, 1876, December . 5.76 ,, 22 ,, 1896, September . 5.54 ,, 23 ,,

1867, J d y . . . 5.81 ,, 1 2 ,,

--

.\ver. age.

in . 1.80 1.52

1.52 1.61

1.95

1.97 2.45 2'33 2.25 2.72 1.29

December i 1.9 j

Year . . /2j . j6 I - I- -~ ~

___ PCl-

cntage of ' J lns i

Yearly mum .\ver. aqe. '

"I ,o In. 7.4 4.35 6.2 4 0 3 6.2 ' 405 6.6 4 3 5

s.0 ' 4.37

8.1 6.07 10.1 6.75 9 6 j j y 9 2 5.54

11.2 7.65 9.4 600

$0 1 5.76

I000 35.54 -- -

I

1877

1851

I829

I 566

I 865

1903 ISSS I 878 1896 ISSO 1852

1876

__ 1903

--I--

laxi. num.

-

2j 22

22

ZI

22

'3 36 29 23 37 24

'3 - i14 ~-

year, i Mini. mum.

~-

I s9s l 1 9 0 2

I S60 I888 I S48 1S96

1S72

I 865

I 848

I553

-

5 3

3

5 I 4 5

6

9

- I I2

Year.

__ IS58 1857

IS52

1S4S

I SS7 1869 I 564 I 565 1S42 I 867

1852

IS58

1821, February , . .04 on 1 day 1891, February . . .05 ,, 4 days 1317, April . . . .06 ,, 4 days 1318, August . . . .07 ,, 1 day 1855, April . . . .09 ,, 4 days 19-10, April . . . . lo ,, (?) ,,

MOLTHS.

1825, July . . . . I0 on 1 day 1893, April . . . . . I2 ,, 3 days 1865, Septembcr . . .16 ,, 1 day 1852, March . . . .li ,, 3dsys 1857, February . . .SO ,, 3 days

January . . I-'ebriinry . . A r m 1 1 . . April . . .

June . . . h lny . . .

Ju ly . . . Augtl4 . . Septetiilxr . . Octolwr . . i\;ovc1nl,cr . . Dcccnilxr . . Total-. . .

Number of Heavy Mciithly Fnlh.

Exceeding I Esceeding + in. 1

I

2 1 2 ,

I 2 4 6

12 8 5

' 9 1

: I I 73

5 in. ~ _ _

. . .

. . .

i 2 I 6 9

2

24

Number of Light Jlonrhly Fall..

Le5s !hail ~ Ler, \tian I.rs,than 1 I 0 . 3 111. , 0.5 in . 1 111.

I 25 74

Tlie subject of rainfall has been dealt with so thoroughly by Symons and others that it is probable that no new points have been brought out in the present paper. But i t is evident that this is an incomplete inquiry. The daily rainfall, which has already been subjected to analysis to a certniu extent by Glaisher, still remains for investigation. I fear, however, that I am in danger of exceeding the limits allotted by the Society, but should be glad to be permitted to continue the subject a t some future time. In bringing this inquiry temporarily to a close, I wish to express my thanks to the Astronomer-Royd for his courtesy in allow- ing me to include the results of the observations contained in the early journals, and for affording me facilities for referring to the Royal Observatory manuscripts. I have also to thank the Council of the Royal Meteorological Society for allowing me to refer to the Belville journals and to make extracts relating to observations of rainfall, which have been of the greatest service.

NASH-GREENWICH RAINFALL, 16 15-1 903 299

APPESDIX.

[On account of references being frequently iiiade to the records of Belville'a and other gauges in the vicinity of the Observatory, it has been considered desirable to give these records as a n appendix to the paper.]

TABLE VI.--blr.. J. 11. I~ELVILLE'S RECORD AT YAIXOCS PLACES I N GI~EENWICII. [162S to 1833, February, a t Park Terrace ; 1633, March, to 1540. August, at Black-

heath Road ; 1840, September, to 1844, .January. at Prior Strect ; 134 I, February, to 1856, June, a t Hyde Vnle.] (Estracted from IWviIZe's Joztr1tul.)

N.B.-Several of the monthly records in 1826 appear to be those made at the Royal Observatory ; and in 1629, December, the snow which fell near the end of the month does not appear to have been measured till January 1830. (See note relating to t h e Observatory record for 1829, December. \

Mr. Belville's station a t Park Terrace was about 600 yards N.N.E. of the

The station at Blacklieath Road was about 1350 yards W.S.W. of the

The station at Prior Street was about 715 yards W.S.W. of the Observatory. And the station at Hyde Vale was about 570 yards S.W. of the Observatory.

Observatory.

Observatory.

300 NASH-GREENWICH RAINFALL, 1815-1903

TABLE VII.-!dIL ROGERSON'S RECOnD AT Cnoom HILL, 1834-1853. (Extracted from the Nautical Magazine.)

0.94 2.76 2 . 5 0 , 1.20 1.10 0.90 0.55 1.40 1.35 1.50

- Feh. - in.

0 3 7 2.40 I .65 1.86 1.85 1.45, 1.3b

0.98 I '04

2.89

1.31 1 6 7 3.1; 2.46 0.99

I .03 1.16 0.87

1.65

2.68

I .00

-

-

2.23 1.05 1.00 460 1.70

- Dee. - in.

I a0 0- 40 I .65 1.20 1.60 2.45 0 4 5

2.29 0.74 0.31 040 2.85 1.18 2.05 2.7c 2.13 1.55

0.65: 1.9; ... -

1.4: -

1.81 2.40 4-14 0.32 2.25 1.61 1-25

3.46 0.24 2.39 4 2 7 2.62 2.47

Ian. - in. a95 a 60 1.70 2.45 0.80 1.25 2.92

2.98 1.07 1.25 3.19 2.48 3.09 1.34 1.43 1.67 1.35

2.Y6 3.22 2.05

2.03

-

2.12 1.18 1.27 2.09 2.03 0.67 1.44 3.96 0.32

I 0.98

Mar.

2.00

0 4 0 3.02

Apr. May. June.

a g o 1.20 1.80 482 1.41 ~ 2.69

1 ~ u ~ y . i A U ~ . Sept. ' oct.

in. in. 0.80 0 4 4 3.80 3.85 2.96 3.85 1.15 2.308 2.65 1.80 4 5 0 1.75 2.65 1.50

-- Nov. iearly

rotais. - in.

3.00

2.45 420 0.95 2.50

1.70 1.85 4.10 1'94 3'23 5.21 2.33 5.09 0.42 1.79

2.43 4 4 2

I *oo

I .02

. . .

- in. 485 0.25 1.55 1.50 1.85 3'44 I .58

4.3 1 2.74 2.55 3.06 2.04 1.74 0.71 2'35 3.38 2.80

4.38 2.24 ... -

2.49

in. o 60 230

0 4 5 0 9 5 1.65 0 3 3

1.28 2.15 0.52

3.05 1.47 1.03 a 7 4 3.29 0 4 5 0.19

4.3 7

1.18

2.00

0.12

in . 1.25 I .96 2.25 I .60 3.00 400 2.70

in. 18.06 22.49 24.81 1971 22.w 27.54 18.24

32.76 24.26 25.75 27.24 24.13

18.1, 32,64 25.1C 2041

22.7f

34.3c

27.3:

... - 246:

1.91

I 436 0.38 0.70 2.99 0.86

0 . j I 386 5.50~ 4.02

429 1.56' 4'73 0.45 4.501 2.13 1-14 4.08' 4 7 0 2.15 1.35 2.58 1.92 5.27 1.33 1.77 2 0 3 1.97 2.41 3.62 0.96

1.61 1-55 2.47

404 4.08 1 6.05

3.22 2.93 ~ 1.46

! 0.37 1.44 ~ 0.55

. . , . . . . . --- 2.41 2.81 2.6:

2.50 0.78 1 1.35 0.60 1.86 ~ 4.54 [End of rec ortl.]

1.42 2.61

1534, January and February ; adopted. 1834, June ; printed in the Nautical

[hlr. Rogerson's station a t Crooins Hill was about *-mile west of the

dltryctrine as 0.40 in., altered to I'd0 in. 1837, Febniary ; adopted.

Observntory.]

TABLE VIII.-TIIE REV. GEOME FisHEn's RECORD AT THE ROYAL HOSPITAL ScIIOoLs, 18441858 [1849 WAYTING]. (Extracted from the Greenwich Obsenwtimas.)

July.

in. 2.82 1.91 1.60 0.63 1.73 2.75 2.80

400 2.25 5.36

- Aug.

in. 1.99 2.88 4.27 2.06 3.68 0.41 I -40

- Mar. Apr. , May. I June.

I I YEARS. I Jan. I Feb.

~

in. 2.09

0.91 "45 2.72 2.28 I .40

0.88

1.00 I .00

0.97

in. 2.87 1.29 0.80 0.62 2'99 t i 7 0.20

4.10 0.20

0.98

2.39 ' 2.66

1.19 I .08 1'47 1.30

2.80 3.20 2.13 -

1.47 2.58

1841, January and February ; 1849, the whole year ; and 1853, December ;

[Rev. 0. Fisher's station was about $-mile N.N.W. of the Observatory.]

approxiinate values deduced from the Royal Observatory records.

NASH-GREENWICH RAINFALL, 1815-1903

09 0 70

0 I 1

0 I M l l C L. ~

Diah~ani diowiiig the rclntive positioiiu of the Ri~iii-gauge Stations i i i Gweiiwiclt a i d iieig1il~ourlior)ll.

INDEX TO THE sT.\TIOSS.

1 iliid 1'. Iloynl Observatory, Court- ynnl aiid Library . . . 1815 to 1840

2. Royal Obnervatory, Mnznetic Grounds . . . . . 1841 to 1S!N

3. Royal Observntory, Jlngnetir Eli. clovtire . . , lS!l!l t o 1003

4. Park Terrace (Bel;,ille i) . . 1828 to 1833 5. Royal HospiL?l Ychools (Rcv.

Geo. Fisher) . . . . 1844 to 1S95

301

t i . C~lJUl1:S I1111 (I~OgerSOll) . . 1534 tU 1853 7. Prior Street (Delvtlla 3) . . 1MO to 1Y.M 8. Hydr Vale (Brlville 4) . . 1344 to lS5ii ! I . M:\illtWtotie Hill (Ellis) . . 1848 to 1851

10. Blnckhentlt Ilond (Uelrilie 2) . 1533 to lS40 11. Uartriiouth Plncr, I3l;~rkliratli

(Glaiaher 2) . . . . 1979 t o 19!E 12. Dartriioiith Terrare. I.ewirlinrti

(Glaialier 1) . . . . 1351 to 1x59

- Yearly rotais.

in. 31.9 24.7 1 9 I 21.4

24.28

-

-

[Mr. Ellis's station at Maidenstone Hill was nbout 930 yards S.W. of the Observatory.]

302 XASH-GREENWICH RAINFALL, 1816-1903

TABLE ,Y.--LIR. J. GLAISHEII'H RECOIID AT DABTYOUTR TERRACE, LEWISHAM

1.5

(Extracted from the Reegistrar Gmernl's QrrartcrZy Reports. )

0.7

2.16 ~ 4.64 2.66 1.06 1.91 0.54

0.46 1.38 2.401 1.01 OM 3.00 6.59 3.59

4 5 2 ~ 2.59 I

2.18 0.25

2.04 1.57

2.40 2.81 4.61

3.67 1.05 2.56 0.78

0.70

2.16

1.49

1.16 2.25 oS5

2 .11

3.24 3.62 0.83 1.54 3-06 2.44 3.43 1.27 1.36

2.61 , 2.49 2.23

----

- Oct.

in.

4' 1 4.3 2.6 5.0 I .6 4.3 1.4

- 2.2

...

- Yearly

in. 22.4

29.7 I 9 5 21.8

Totals. -

...

2 1:s

...

__

July. -

in. 3.8

5.9

6. I

1.3 3'0

...

2.1

...

...

Aug.

in. 2.4

2.3 3.3 0.9

2.8

-

...

...

Sept.

in. 0.3

2.4 0. 8

-

...

1.1 ... 3.7

I

;Ipr. ~ hlny. -- in. in.

3.4 1.8 0.7 3.6 0.1 1.8

2.1 1.0 . . . . . .

June.

- in. 1.3

2.7

0.7

...

1.2

...

. . . . . . ~ . . . . . . . . . . . . . ~ --I

(Corresponding Mean for Royal Observatory = 22'50 in.)

[Mr. Glaisher's station at Dartmouth Terrme WRS about 15.10 ynrtls S.S.W. of the Ol~servatory.]

TABLE XI.-XR. J. C:L.\ISIIEII'S R I X O I ~ I I Al' L)AItT3IOUI.l1 PLACE, R I A C K H E A ~ ~ I , 1875-1893. (Extracted from the Registrar General's Quarterly &ports.)

~

Yearly Torals.

in. 2S.OJ

25.90 28.32 28.07 31.39 30.1 I

27.72 28.28 22.55 17.22 22.87 23.82 20.48 27.08 22.81

21.59

25.10 22.89

__

...

-~ \lay.

in. I .44

1.66 3.95 3.37

1.56 1.53 I .70 0.93

422 1.84 0.63 3.21 1.30

2.67 1.65 0 .52

I .98

-

1.22

0.58

2.22

-

-

__

Oct. Nov. ' Dec. I -

in. 1.54 1.60 3.29 3'57 2.64 2.21

0.49 2.67 1.73 1.12 2.02 1.29 1.50 1.55 1.S6 1.67

0.76 1.39 0.08

I 4 3

-

-

- in.

0.70 2.66 2.47 0.96 0.70 0.48

1.59 1.31 0.78 1.24 I .46 0.99 1.09 2.53 1.29 1.80

2.19 1.03 0.40

I .40

-

-

1875 1876 1877 1878 1879 I880

ISYI 1832 I Y S j 1884 1885 1886 1887 I SSY I 889 I 890

1891 I 892 1893

Means 1875.1892

--

in. 0.95 1-77 1.78

3.95 2.36

2.51

2.64 1.25 2.18 0.56 0.68 1.06 2.32

0.07 1.65 2.80

I .62

1.12

1.21

1.10

-

-

in. 3.98 1.72 I .98 I .80 0.84 7.91

2.97 6.53 "54 I .08 3.1 I 1.52 1.07 1.26 393

4 4 5 3.99 [End

2.82

1.11

-

in. 2.99 3.13 3.60 3.53

2.04

2.47 2.50 3.12 1.18 2.70 305 3.98 3 7 4 0.80 1.48

I .oo

2.00 2.30 i f rec

2.53

-

in. I .24 5'92 1.82 1.32 0.64 2.79

2.74 2.03 0.76 1.99

3.81 I .49 0 9 1'35 0 6 9

2.52 1.19

ird.]

1.90

1.01

_-

in. 3.1 I 1.17 4.37

2.47 0.33

2.16 1.16

1.75 1.73 1.15

3'45 1.14

0.95 0.82 1.84

1.59 o 40 1.31

I .70

1.01

-

-

2.03 2.81 1.47

1.51

0.47 1.25

3.50 2.13 2'79

2. I I

25.24 -

(The sum of tile twelve monthly Neniis is 25.2'1' 1n.j

[ A h . Glaisher's station was nbout $mi le S.S.W. of the Observatory.]

DISCUSSIOK-GREENWICH RAINFALL, 1@15-1903 303

DISCUSSION.

THE PRESIDENT (Capt. D. WILSON-BARKER) reinarked that Mr. Nash had done excellent work in bringing such an interesting paper before the Society. He waa sure they would all look forward to the further inquiry on the subject, as suggested by Mr. Nash towards the end of the paper.

Mr. W. hIaRRIOTT exhibited on the screen lantern slides showing the position of the various gauges at the Royal Observatory, and also portraits of the Astronomers-Royal, Sir G. B. Airy and Jlr. W. H. Christie, F.R.S., and of the JIeteorological Superintendents, Mr. J. Glaisher, F.R.S., Jlr. W. Ellis, F.R.S., and hIr. W. C. Nash. He also showed the various patterns of rain-gauges employed, and referred to the time in his own experience when the monthly iiieasuremeuts were made by dipping a stick into the collected rain-water and measuring off the wetted portion. The slides also included one showing the iiiean monthly rainfall for the 89 years 1815-1903, and another illustrating the fluctuations of the mean 10 yearly periods. This latter slide clearly proved that a 10 years’ average was not of sufficient length to give reliable information.

JIr. W. ELLIS congratulated hlr. Nash on having presented to tlie Society a paper containing so valuable a table of rainfall for Greenwich. Rainfiill was a subject to which JIr. Nash had paid niuch attention, and the present table was not the first that he had put forth, a former one for the years 1841 to 1879 having appeared in Eritish Rainfall for the year 1859. The present table is thus an estension forwards to the year 1903, and backwards to 1815, giving now a table for the Royal Observatory for 89 years. A h . h’ash seems to fear that his table may have exceeded available limits, but if his discussion of the results had been yet further extended he, hlr. Ellis, was sure that this would have been also gladly received. The value of the table consists in the circuni- .btance that we now have a consistent treatment of the rainfall of the earlier years, 1815 to 1840, during which period the record was not an official one, but was maintained by the assistants of the Observatory for their own informa- tion, and various points regarding position, etc., had to be carefully inquired into and considered, a work that no one, he was sure, could better have performed than hlr. Nash, because of his intiinate knowledge of the history of the matter. He did not propose to speak much of details. hlr. Marriott’s lantern slides had clearly brought out some features ; he had, however, divided the 89 years into four periods of 22, 23, 22, and 22 years, and found the separate annual means of these groups to be 24-92 in., 24.17 in., 25.50 in., and 22.87 in. respectively. Combining the means for the first three periods, we get a general mean of 21.86 in., that for the last period is thus two inches lower, a consider- able falling off for a 22-years’ mean as conipared with that for 67 years. Again the greatest annual fall n-as 35.54 in., and the least was 16.38 in., less in amount by more than one half. These were serious variations for those to consider who had to deal with questions of water supply. The curious fall in the mean monthly values from July to September he had found to be in close correspondence with what was observed at Camden Square. He was sure that the Society would be glad to have this table in the Quarterly Journal, and he hoped that Mr. Nash would in due time carry out his idea of dealing with the much more difficult question of daily rainfalL

Mr. F. J. BRODIE considered that the Society was greatly indebted to Mr. Nash for the valuable information given i n the paper. Last year, when the subject of rainfall attracted the notice even of “ the man in the street,” numerous inquiries were made aa to how matters stood in comparison with earlier years. Towards the close of the year the hleteorological Office record for London,

304 DISCUSSION-GREENWICH RAINFALL, 1315-1903

extending back to 1866, was enaily beaten, iind recourse was naturally had to the longer series of observations made at Greenwich. 111 such circumstances it IVU rather disconcerting to find that while a published record existed for as long back as the year 1815, some of the earlier values were so doubtful that they could not be quoted with nny degree of contidence. A h . Nash had now furnished a more reliable set of figures, and under the sanction of such an authority, the new values might doubtless be accepted as very nearly, if not absolutely, correct. Some doubt appeared to attach to the values for the years 1867 oiid 18G8, aiid at the end of the long table the author hod supplied figures which he considered l ime reliable. These vnlues might perhaps with advantage have been inserted in the table in the place of the less authentic ones. The question ns to the length of period required to yield an absolutely reliable average was still to son18 extent an open one. In the very valuable paper on rainfall recently presented to the Institution of Civil Engineers, Dr. Mill had suggested the 30-year period, 1570-09, as yielding satisfactory mean, and had given excellent reasons for holding such a view. The subject was, however, an extreriiely difficult one, and would in all probability continue to exercise the niintls of i~icteorologists for a long t h e to come. The expression, a ‘6 rainy clay,” as applied to all cases in which the fall rexhetl’ so trifling an amollrlt even as 0’01 in., seenied objectionnble. In some of the recent publicn- tions of the Meteorological Office the term (‘ raiu day had been substituted. He (hlr. Brodic) wiu inclined to lavour the use of the expression, “ a clay with rain.”

hlr. C. HARDIW said that he liad for inany years used the Greenwich records for coniparisan with the London reiidiiigs, both for pressure a’hl teinperature as well as rainfall. They were good observations and carefully taken. In his own manuscript copy he had been in the habit of putting a + or - sign against the rainfall, SO that he coulcl see at a glance which montha were aliove or below the average. The only year that was above the average for the past 10 years was 1903, and going back as far as 20 years tl,er\! were only three others. The December values were, however, as a rule, in excess, the other months showing the deficit. He would suggest that sonie difference in the type might be made in printing the tables, so that any one searching for ftlcts miglit rcnclily see which months were above or below the average.

Dr. H. R. MILL said lie would like to express his high appreciation of the value of the work dolie by Mr. Nnsh. I t was n good thing to get observations taken, but e v e n better to rescue a long series of records from unjust suspicion. The whole Greenwich record could henceforward be looked upon with a degree of confidence not possible before. He would have liked to see clearly set out the corrections that had been applied to tlie original figures, and the reasons for their use, as some differences of opinion liad arisen on the matter. He had worked out the ratio of the three driest years to that of the whole period, and the figures came out at 85 per cent. The usual proportion of the average of long records had been found to be 80 per cent, and this excess of 6 per cent. ww a comparatively large difference. He hoped that Jlr. Nash would go on to discuss the daily rainfall. He was pleased to hear the various opinions expressed as to the term “rainy days.” He hiiriselt would like to drop the (‘ y ” in the word rainy. I t was necessary to have a concise term, but, speaking genern.lllly, he did not think any one was now misled by the phrase.

Dr. H. N. DICKSON remarked that every other speaker had an official con- nection with Meteorology, but as a “ country cousin ” he would like to express his satisfaction in possessing in SO complete a form the information prepared by Mr. Nash. I t was exceedingly difficult for private individuals to attempt the preparation of papers like the present, owing to the difficulty of access to the ohservations, although they were always conscious of the courtesy of the officials

DISCUSSION-GREENWICH RAINFALL, 1815-1903 305

in assisting those whose work kept them a t a distance. He was very pleased to see this authoritative statement of the Greenwich rainfall, and was keenly sensible of its value. It was interesting to note the distribution of the monthly rainfall during the dry years, and it was noticeable that the drought of the last ten years was mainly that of the summer months. The rainfall in the winter was more nearly up to the normal amount. With regard to Mr. Harding‘s suggestion of typographical differences in the tables, he thought it would be best to leave them as they were. He himself had suffered a great deal, especially with regard to maps, in working with figures that had been thus treated, and had found the plan a very disturbing element. This was especially so when the precise average was not definitely known.

Mr. W. C. NASH, in reply, said that he wished to express his thanks for the kind way in which the paper had been received. He did not like to include the amended figures for the years 1867-68 in Table I., ns he was not qnite sure whether they were perfectly reliable. Respecting the “rainy days,” the term itself was somewhat misleading, but in the present paper he hnd included amounts of ’005 in. ant1 upwards as representiiig a ‘ I rainy day,” in accordance with the rule aclopted by M r . Symons. There were, however, not very niany days of such siiiall rainfall as *005 in. To indicate the difierence froiii the average in the tables typographically wonlcl be rather a ditFicult matter, as two different types had already been employed in the paper. AIr. H. Sowerby Wallis, in his paper on the Cnmclen Square rainfall, 1858- 1902 (Bvilish Rainftll, 1902), had already made a coinparison between the Greenwich aiid Camden Square averages, and in relation to tliis he \vould like to draw attention to a comparison he liad made between the monthly arciages for the 89 years, 1815-1903, for Greenwich, and those for the 33 years, 1871-1903, for Greenwich and Brixton.

___.___-

NONTHS.

! -~

1 .\far,ch. . .

, January . . ~ February . .

Aprd . . . May .

August . . .

June . . July . . .

September . . October . . November . .

I December . .

in. I .so 1.52 I .52 1.61 1.95 I .97 2.45 2.33 2.25 2.72 2.29 1 1.95 ~

,

in. I .82 1.59 1’49 I .66 1.71 2.18

2’45 2.38

2.80 2.34

2.12

2.02 ----

In conclusion, the agreement between the average number of rainy days for the London district, as based upon different series of determinations, was dwelt upon, and the following table was adduced (see next page) :-

Y

306 DISCUSSION-GREENWICH RAINFALL, 1815-1003

~ I O N T H S .

Average Number of Rainy Days.

Greenwich. 1 London. I Camden Square. 63 years, 1841-xgo3. , 56 years, 1807.1861.1 45 yeys, 1858 .rpa .?

. .

March . . . April . June . July . . . August. . . September . October . . November . . December

May .

148 I 2.4 13.2

12.4 I 1.6 12.6 12.9 12.3 15.1 14.0 142

12.0

13.4 12.4 I 1.9 12.8 I 2.7

13.0 I 2.9 12.7 14.4 I 3 6 I 3 6

12.0

'5.3 13.2 13.4 12.3 12.4 I 1.7

I32 12.5 15.0 14.0

15.3

12.2

1 Vernon, Li f . and Phil. Socirty o/illanchrstrr, 1861-61. Vol. 2. Third 2 Wallis, British h'aipifnl/, 1902, p. 34.

Series, P. 335.

Frost Effects at Niagara.-Mr. Orrin E. Dunlop, writing from Ningara Falls, sends u s some striking photographs of ice formations noticed n t Ningnra during the past winter. An ice bridge fornied in the gorge below the Falls in December last, and thousands of persons crossed froni shore to shore on this curious formation. Another remarkable object was an ice mountain coiiiposed of a Inassivc collection of frozen spmy. Usually this mound rests on the ddbris slope between the inclined railway building and the falling water, but last winter it bridged the torrent of the American Fall and estended over in front of the Fall. Here a grotto-like effect was caused by the wearing tendencies of the falling water, and the effect was repeated on the outside or ice bridge side, of the mountain. From the ice bridge the different layers of ice that went to make up the mound coulrl be distinguished. A part of the cliff over which the American Fall usually flows was hidden under hugh icicles that hung from the brink t o the talus at the foot of the precipice.

In Prospect Park the ice that gathered on the treea was very destructive. The ice grew so heavy that the largest trees lost ninny branches, and sonic were left with only their trunks. Tlie grandest sight of all wns, says hlr. Dunlop, a t Prospect Point in the middle of February. The wind blew from the South- west, and the spmy of the American Fall fell upon the Point, where it was frozen with great rapidity. Every hour added to the mass, until finally it was more than 30 feet high froiii the water as it plunged over the American Fall. The mound extended back into the park, half-burying trees that were already weighted with great loads of ice. Realising that the inound might damage the lower section of the inclined railway building or cause loss of life among the many who climbed about the ice and n~ountniii below, it was resolved to try to blast i t away. To accomplish this, holes were drilled along the upper river side, and eight sticks of dynamite placed in them ; but their explosion accomplished little, owing Co the slight resistance offered by the ice.- Nutwe, March, 24, 1904.