240 Scientific Intelligence. 
when the diurnal range is increased, and diminished at the time 
of a sun-spot minimum, when the mean diurnal range is dimin- 
ished 
ed. 
The evidence in favor of this final conclusion is considered as 
not entirely decisive; the other conclusions are regarded as sufti- 
ciently certain. 
10. U. 8. Coast and Geodetic Survey, Caruice P, PatTErson, 
Superintendent in charge. ethods and Results: American 
Standards of Length (Appendix, No. 12—Report for 1877). 
36 np. 4to. Washington, 1880.—This memoir contains the report 
by Professor J. E. Hilgard on the details of observations made to 
establish the relation between the American and British stand- 
ards of length. The general results reached (published in Pais 
T r 
dix 22, Report for 1876), show—(1) That there is no difference 
d, No. 57. 
1814), is a bronze bar, 86 inches long, 24 inches wide, and 4 inch 
thick, it has an inlaid silver scale; it was made for the survey of 
the coast of the United States. The yard of 36 inches, between 
the 27th and 63d inch was adopted as the standard yard of the 
United States by the Treasury Department, in 1832. The two 
other standards were presented by the British Government 10 
1856. 
_A detailed discussion is given, in the report, of the coefti- 
cients of expansion of the three standards, and of the a fe 
have been subjected to 
great variations of temperature, varying fully 75° F. Asa result 
great rigidity, of Baily’s metal consisting of 16 parts copper 2 / 
parts tin, and 1-part zine, and it is suggested that the molecules © 
yield under changes of temperature, and perhaps in less degree ‘ 
the simple effect of continuance, The wrought-iron bar, No. 57, 
inane 
ia ces aa a Aaa) 
