68 SCHOOL SCIENCE AND MATHEMATICS
c- F- A LABORATORY THERMOMETER SCALE.
125^25? BY J^^ BROADHURST,120^^248 Teachers College, New York City.no-==239
-p^ accompanying illustration shows a Centi-110-230 grade-Fahrenheit thermometer scale designed
for ready reference in the bacteriology, physi-io5__-^_g8i "* ^^^j x^.^x^x^ Aix tiic ucu^Lciiuiugy, pnysi-
^cal science, and domestic science classes at
100J~212 Teachers College. Centigrade and Fahrenheitequivalent are given for the temperatures mostoften needed by such students.The scale is printed on narrow slips of rather
stiff paper, and can be used as a book mark orso^ire pasted inside the cover of the laboratory book.
-i67 The reverse side contains directions for chang-ing from one scale to the other1: To convertdegrees Fahrenheit into degrees Centigrade, sub-
65 Lu5 tract 32. multiply by 5, and divide by 9. To140 convert degrees Centigrade into degrees Fahren-
heit, multiply by 9, divide by 5, and add 32.
Several high school text books in physics give60n122 Iwo parallel thermometers. They are all drawn
,^3 to a very small scale, and lack, so far as I know,any emphasis of the important temperatures.C1,14.1.)- .i_-__.i
L - _ 1 1 . l /.
-^ 3^B "^stitt?s text book in bacteriology (designed prin-
35 P 96 cioallv for medical students^ p-ivpo Q^pral ownr.c35-95cipally for medical students) gives several groupsso
soof equivalent temperatures, but drawn to vary-25 JE^^^-nm^ scales. The markers illustrated above make^^1^72no claim to originality it is hoped, however, that
20~^~^they may prove a handy laboratory aid.
iThe Editor of SCHOOL SCIENCE AND MATHEMATICS prefersthe following method of making the transformations Since40 is the only temperature at which the temperature in
=41 either scale is represented by the same number,40 C or Fw to change a Centigrade temperature (100C) into Fahrenheit, add40 , multiply by 9, and divide by 5, after which subtract 40
-88 To change 248 F. into Centigrade, add 40, multiply by 5, anddivide by 9, after which subtract 40. If your cut included-23 ^O0 both methods could be" taught from it."