414 , REPORT—1883. 
If successive values be given to ¢ from +o to —o, the corresponding cubics 
and quartics may be drawn from (A) and (B); their combinations determine the 
twelve values of &, n, real or imaginary. 
Or the ratio € : 7 may be thus obtained without drawing. 
Write (A) and (B) in the order of their homogeneous terms : 
Uz + Uy +U, =0, 0, +0, =0. 
Their eliminant is of the ninth order, homogeneous in € : 7: 
2 oe 
Dy Uy — VVgly + Vq"U, = 0. 
= . if , : 3 
By giving successive values to (=): the nine values of £ may be found in 
each case, and by aid of (A) or (B) the separate values of &, n. 
Linear expressions were found for x, A by the original differentiations of @ in 
terms of &, 7, a ; when the several values of these last variables are substituted, 
x, A can be obtained correctly. 
5. By this method the curve (D,) has been drawn when p=q=0, ze. for the 
duals of bicireular quartics, and was exhibited. 
Tn this case the curve (A) becomes a quadric, and the homogeneous equation 
in €: is reduced to a quartic, which may have four or two real values. 
MONDAY, SEPTEMBER 24. 
The following Reports and Papers were read :— 
1. Sixteenth Report of the Committee on Underground Temperature.— 
See Reports, p. 45. 
bo 
. Report of the Committee appointed to co-operate with the Scottish 
Meteorological Society in making Meteorological Observations on Ben 
Nevis.—See Reports, p. 125. 
3. On the Completion of the European Portion of the Preliminary Meteoro- 
logical Catalogue. By G. J. Symons, B.S. 
4, On the Heat of the Sunshine at the Kew Observatory, as registered by 
Campbell’s method. By Professors H. E. Roscor, F.R.S., and 
Batrovur Stewart, /.R.S. 
On June 10, 1875, we communicated to the Royal Society a paper containing 
the observations of the heat of sunshine made by Campbell’s method during the 24 
years 1855 to 1874, and we now communicate to the British Association a second 
series of such observations made between 1875 and 1882. 
’ The following extract from a Parliamentary Report will explain the process 
adopted by Mr. Campbell :— 
‘A hemispherical cavity is made in a block of wood, and a spherical lens is 
placed in this cavity in such a position that while its centre coincides with the 
centre of the cavity its chief focus is at some point of the hemispherical concave 
surface, the exact point being of course determined by the direction in which the 
rays strike the lens. 
‘ Whenever, therefore, the sun shines, a portion of the wood will be carbonised 
