and Strength of Materials. 265 
In the third experiment, 
45 29 :: 225: (93)¥='45. T= 35 = .840. 
In the fourth, 
0 2.9) > 2, 120.5(90)*— 3B, «4% w = oF — 798. 
In the fifth, 
20: 35:: 120: (380)"= 210. ws en =P Ee 
98. And the mean of these ultimate values 
.  984-4-.953-4. 798-4.901 
aia = ssi haath aly aie — .895.* 
29, By the same reasoning too we found 
the mean value of » in these experiments, 
when the weights were : those of fracture 
‘ : .92-+.88-+1.00 : 
& Seb TE ee 95 nearly, which 
may with very trifling error be assumed 
unity. 
30. But it was suggested to me by Mr, 
Dalton, that the iron might possibly be di- 
lated or contracted to such a degree in these 
experiments, as to render it necessary to cor- 
rect them. 
* The reader will easily pereeive that the above ultimate 
value of w, and that of wv in article 25th, can, strictly 
speaking, apply to no other form of beam but that of a joist; 
they are nevertheless of considerable importance, and will 
enable us to form an idea of the quantity of the error which 
would arise from supposing the extensions and compressions 
to be as the forces.—See Exam. 3rd, Art. 34th. 
Ll 
