Form of Temperature Wave spreading by Conduction. 363 



sphere 0'091 cm. in radius, or about 3" 16 mm. 3 This volume 

 may be regarded as a measure of the "incendivity " of the 

 instantaneous point source o£ heat (with respect only to 

 its ability to disseminate heat by conduction), for com- 

 parison 'with the other hypothetical sources shortly to be 

 discussed. 



The time at which the temperature of the gas at a distance 

 0*091 cm. from the origin reaches its maximum (namely, 

 700°) is about 0-00275 sec. The form of the temperature 

 wave at this time is shown in fig. 1, curve A, in which the 

 abscissae are values of r, and the ordinates temperatures. 



FiR-. 1. 



4CCO p 



3COO 



: r b 



/4 . //?sS iaot^n eo us fo/h t 



Cort/oueo 1 Po/ht Sour 

 C. /osts/7 igneous Spher/'ca 

 O. /ostsntaneous Spher/cay 



<arce. t = OOP 75 sec. 

 •ce. Z~=-OOS sec. t=00<5sec. 

 ' Surface Source. t-OOOSsec. 

 ISo/ume Source. t = -OQ2sec 



The distribution of temperature due to different quantities 

 of heat supplied instantaneously at the origin is easilv 

 calculated from Table I., the temperature at any place and 

 time being proportional to Q. 



II. Continued Point Source. 



The solution of equation (1) for the case in which heat is 

 supplied at the origin at a uniform rate q per second for a 

 time interval T is obtained by integration from equation (2). 

 When the time t, for which the temperature is calculated, is 

 less than T, the solution is 



6 



~ q jo8c(irktf 



fit. 



