68 Major W. T. David on the Calculation of 



3. The radiation emitted was measured in three positions 

 on one of the end-curves of the explosion vessel, viz. at the 

 top (position A), at the bottom (position B), and at the centre 

 (position C) . The radiation measured at position C was a 

 little greater than that at either A or B ; and that measured 

 at A was a little greater than that at B. The mean value of 

 the radiation received at A, B, and C gives a fairly accurate 

 estimate of the average radiation over the whole vessel. 



4. When the bolometer was placed close up to the window 

 of fiuorite the radiation it received per sq. cm. of its surface 

 was equal to that received by a sq. cm. of wall surface in the 

 immediate neighbourhood ; and when the bolometer was 

 placed some distance away from the fiuorite plate the radia- 

 tion it received came from a cone of the gaseous mixture of 

 small solid angle (N, as shown in fig. 1). Throughout this 

 paper the radiation measured with the bolometer in the latter 

 position has been divided by the solid angle of the cone so as 

 to give the radiation from a cone of unit solid angle. The 

 rate of emission from a cone of gaseous mixture of unit 

 solid angle has been called b} r Prof. Callendar the intrinsic 

 radiance. 



Fio-. 2. 



Time from lan/t/on 



5. A list of the symbols used in this paper is given below. 

 In defining them it will be convenient to refer to the curves- 

 in fig. 2, which have been taken from a typical record. 



