BY HEAT or "VVATEE AND MEECrET. 



235 



0° and 100° may be considered for these rods as proportional to increase of tempera- 

 ture. 



No. 1. The observation Tj, a, and b was taken whilst heating the trough for Experi- 

 ment No. 4, Table I. 



No. 2. The observation T^, a, and I was taken whilst heating the trough for Experi- 

 ment No. 5, Table I. 



No. 3. The observation Tj, a, and h was taken whilst heating the trough for Experi- 

 ment No. 7, Table I. 



No. 4. The observation Ta, a, and b was taken whilst heating the trough for Experi- 

 ment No. 8, Table I. 



It was not easy to obtain a constant temperature for Tj ; the values for Tj and a are 

 therefore the mean of two or more readings. 



Table I. 



Table II. 



T,, T2, T3 denote the true temperature of the water. 



a and b, the true expansion of the rod between those temperatui'es, expressed in mil- 

 limetres. 



The last two columns give the expansion of the rods, calculated from the respective 

 observations for 100°. 



The length of the two rods was the same, namely 1825 millimetres, and their dia- 

 meter about 20 millimetres. 



The increment in length for 1 metre will be therefore between 0° and 100°, 



0'"-729; 

 2k2 



