TRANSACTIONS OF SECTION A. 339 
The variation is then assumed to depend linearly on the number of sun-spots, 
uhd the following equation used to separate that part depending on the sun-spots 
from the other or normal part :— 
a=a)+ va, 
where a is the total daily variation 
a, is the normal daily variation 
v a constant proportional to the spotted surface of the sun: 
a, the daily variation due to the sun-spots. 
9. Can the Earth’s Motion through dither affect Material Phenonena ? 
By Professor J. Larmor, Sec. 2.8. 
JOHANNESBURG. 
TUESDAY, AUGUST 29. 
The following Papers were read :— 
1. The Origin and Progress of Geodetic Survey in South Africa, and of the 
African Arc of Meridian. By Sir Davi Git, K.C.B., F.R.S.—See 
Reports, p. 228. 
2. On Winding Ropes in Mines. By Professor Joun Perry, #.7.8. 
When a cage is descending, and the upper end of the rope is suddenly stopped 
what occurs in the rope? And, especially, what is the tension at the upper and 
lower endsP The solution was given the author by Professor Love, and was 
extended by a pupil, Mr. Richardson, who has drawn curves for a given case, 
comparing the results with an approximate simple solution, These curves were 
exhibited, Because internal friction and yieldingness of attachments are neglected 
in the mathematical problem, it is probable that the simple solution is more 
correct in all cases where the calculation is important. Reference was made to a 
paper read in Section G, in which the author used the simple solution, and proposed 
a method of preventing accidents in mines. 
13. On the Present State of ihe Lunar Theory, and on the Formation of a 
New Set of Lunar Tables. By Professor E. W. Brown, £.2.S. 
4. The Value of the Secular Acceleration of the Moon derived from the 
Early Eclipses of the Sun, By E, Neviu1. 
5. On the Density of Matter in Space. By R.T. A. Innes. 
The author showed that, adopting the most probable figures for (a) the number 
of molecules in a cubic centimétre, (6) the number of stars and their masses, and 
(c) the extension of the luminiferous ether, the density is of the order of one molecule 
to every 800,000,000 cubic centimétres of space. 
Z2 
