400 SEVENTH REPORT—1837. 
Results in the preceding Table, showing the progressive and 
increased ratio of deflections from the 11th of March, 1837, 
to 23rd of June, 1838. 
ss Sie oc Sd 2 SS ES 
1 tI | Hot Blast Iron ey 
Sena tea i. ™ | Date of her: Fae deflection in ” | Ratio of increase of 
inches. ee inches. deflections. 
1:270 March] 1th,1827))......... 1-461 
1-316 June 3rd, 1838)} 78° 1-538 
“046 Increase, = |\seccesses 077 1000 : 1673 
The ratio of increase is here much greater than what is indi- 
cated by the lesser weights—280 Ibs.—in Table, No. XI.- The 
progression towards fracture (providing we assume a progress- 
ive yielding in that direction) is advancing at a quicker rate in 
this case than with the lighter loads; consequently the resist- 
ing powers are becoming gradually weaker. We must however 
observe, that the temperature of the air in the room where the 
bars are placed was at 78° when the last observations were made, 
whereas the temperature was only 46° at the time the bars were 
first loaded. This difference in the temperature will give rather 
greater deflections, from the expansion produced on the bars in 
a medium of 78°. In confirmation of this opinion I would beg 
to refer to the observations of November 18th, when the atmo- 
sphere of the room was at 45°; the deflections had then decreased 
from 1:288 to 1*286 in the cold blast iron, and from 1°504 to 
1°499 in the hot blast iron. 
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