456 Experiments to determine variations in length 
ished its length to 80" less than its initial length. The bar was 
kept constantly in melting ice for one and a half days, during 
which time no marked change in length occurred; but expos- 
ure to the air of the comparing-room for an interval of one day 
was followed by an increase of 15” in the bar’s length, leaving 
it still 15” shorter than its initial length. 
3d. The bar was exposed to an air temperature of about 70° 
F. for four hours and then cooled to the temperature of melt- 
ing ice. This increased its length 26” over the length it had 
= the previous day, leaving it 11/ longer than its initial 
ength. 
4th. The total range in temperature to which the bar was 
subjected was about 216° F. tal range in length of the 
Differences in Length of the Steel Meters. 
Date, 1883. | §,—S8, Mean. Remarks. 
February 12 +11°0 fe 
oy 13 + 96 + 99 Before heating 8; 
tc 14 + 90 
* 15 + 99 : 
After heating 
ee. 10° oy 
ot 18 : va +9 8, to near 212 F. 
as 23 + 92 
c 25 +12°1 : After cooling 
Soa §, to near -6° F. 
