90 



PRINCIPAL FORBES ON AN EXPERIMENTAL INQUIRY INTO 



78. Graphical Interpolations. — The observed excesses of temperature (as ob- 

 tained, for example, in the preceding experiment for the central hole) were pro- 

 jected in a curve of which the times were taken as abscissie, and the independent 

 temperatures of the bar as ordinates. When more than one series of observations 

 (on the same bar at different times) were to be combined, a procedure exactly 

 similar to that described in Art. 57 for the stationary temperatures was emplo}'ed ; 

 that is to say, one series being first projected on the engraved paper as funda- 

 mental, any other series was next similarly projected on tracing cloth, and the 

 system of points thus obtained was moved to the right or left over the first, until 

 the points in the two curves appeared to be superposed satisfactorily. The inter- 

 polated observations were then pricked through, and a curve drawn through 

 the whole. 



TABLE V. — Curves op Cooling (in Terms of Time). 



Time from 



■ E I. 



Cask II. 



1J inch Bar, 



covered. 



III. 



Arbitrary Origin. 



1^ inch Bar. 



1 inch liar. 





March 26. 



b 29. 







-10 Min. 



... 



; 242-3 







- 5 



, m 





*221-4 



*263-9 



... 



- 2-5 







*2ll-5 



*243-6 



. . . 











*201-9 



"225-0 



"258-5 



2-5 







1920 



*207-7 



243-3 



5 







1835 



*191-8 



-2289 



7-5 







1748 



177-0 



*215-3 



10 



1673 



166-5 



163-6 



202 4 



12-5 



159-1 



158 2 



150-6 



190-05 



15 



151-4 



150-6 



1391 



178-7 



20 



1370 



1365 



119-25 



15755 



25 



124-2 



124-2 



10295 



138-9 



30 



1126 



112-8 



88-8 



122-45 



35 



40 



102 6 



1025 



771 

 670 



108-6 

 96-45 



93 7 



50 



786 



50-95 



77-25 



60 



65-9 



39-4 



62-2 



70 



55-8 



30-65 



50-5 



80 



47-3 



24-25 



41-3 



90 



40-5 



19-2 



33-95 



100 



34-9 



15-27 



28-2 



125 



242 



8-9 



180 



150 



171 



5-45 



11-95 



175 



123 



3-42 



81 



200 



8 95 



2-15 



5-55 



300 



2-95 



0-4 



1-4 



400 



1-12 





0-4 



The number* 



5 marked thus * are deduced frc 



m the Equation 



s of Art. 88. 



