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 at100J~212 Teachers College. Centigrade and Fahrenheit

equivalent 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 or

so^�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.

70���U���168

Several high school text books in physics give60�n�122 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.C’1,14.1.)- .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 Since�40 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."