490 Journal of the Asiatic Society of Bengal. [September, 1908. 
Laboratory which the Government of India are about to establish 
under my charge, I have made 30° C, the standard. We work, o 
course, almost entirely in centigrade, which is a sufficient reason 
for having an integral value for the standard on that scale. 
ae Indian Survey Department are in possession of a standard 
which is kept in the Mathematical stasagea nes Office, 
Uatssten The following is a copy of the certificate 
Dated the 20th calves, 1889. 
This is to certify that the Government of India have ae and 
received from the Standard Department of the Board of Trade an 
accurate copy of the Jpenial Standard Yard, a standard foot, and 
a ee inch, as follow 
LF scientific a5 of the yard at sixty-two degrees 
Plnenbaie’ is determined-by two fine lines marked on the gold studs 
inserted in the brass bar which aemepnene isis certificate, which 
beat bar is marked :— | 
“ Accurate Copy of Imperial Standard Yard, 1889, 
“ Calcutta.” ‘Standard Yard at 85° Fahr.” 
‘At 85° Fahr. the precise length of this yard is 3600039041 
pg and pe one degree Fahrenheit its thermometric expansion 
00003744 
3 ne eae Signature. 
7, Old Palace Yard, 
Westminster, 
The temperature of 85° F, was selected as a standard tem 
perature, because it is a convenient tempera’ of reference in 
the Indo-Gangetic Plain as well as in most localities of the Indian 
Peninsula. Eighty-five ee: was evidently chosen because it lies 
midway between 80° F. and 9v° F., the former temperature being too 
low, whilst 90° F. is ac too high. Unfortunately 85° F. does 
not correspond to an integral value@n the centigrade scale, whilst 
86° F. is the same as 30°C. The differenos of one degree Fahren- 
heit is a very small one for the purposes of the Survey Depart- 
ment, and a change in the standard temperature from 85°F. to 
can be oats cxlon lated. 
I should have liked to make a set of thermographic observa- 
tions in my own laboratory, but I did succeed in getting the 
oan of an automatic temperature reco 
end, Dr. Amrita Lal Sircar, roa Secretary of the — 
Asiciation for the Cultivation of Science, has recorded a co 
tinuous series of temperature observations for a number of aise 
in his Calcutta residence. An inspection of these oe rere 
that ia is @ convenient standard temperature for C 
Of special i t in connection with our subject is a study 
