758 Proceedings of the Royal Society 
day hours which becomes inverted in passing from January to July. 
It follows — 
8. That the principal, if not the only, cause of change in the 
amount of the lunar action at Trevandrum, near the magnetic 
equator, for the moon on different meridians, depends on whether 
the sun is shining on the place of the needle or not. 
The author finds — 
9. That the area of the curve representing the lunar diurnal 
variation in the mean of the group of months, October to April, for 
the half orbit about Perigee, is to that for the other half orbit as 
1T8 : 1 ; while for the group of months, May to September, the 
ratio is 1*31 : 1 ; the moon’s action appearing to diminish more 
rapidly with the distance from the earth, when both moon and earth 
are farthest from the sun. As the mean distances of the moon from 
the earth in the two half orbits are nearly as 1 to T07, it appears 
that the mean range for Perigee and for Apogee, derived from both 
groups, varies nearly as the inverse cube of the distance, as in the 
case of the tides. 
Monday , 20 th May 1872. 
Professor Sir ROBERT CHRISTISON, Bart., President, 
in the Chair. 
The following Communications were read : — 
1. Some Helps to the Study of Scoto-Celtic Philology, 
by the Hon. Lord Neaves. 
(Abstract.) 
Lord Neaves read a paper entitled “ Some Helps to the Study of 
Scoto-Celtic Philology,” in which, after noticing the mistaken 
tendencies of the Celtic scholars of former times, both Irish and 
Scotch, as to the origin and affinities of G-aelic, and adverting to 
the fact now firmly fixed that it was an Aryan or Indo-Germanic 
tongue, he submitted a statement of some of the imitations or 
disguises which words underwent or assumed in passing into G-aelic. 
Thus it was a peculiarity of Gaelic to avoid the letter p, which it 
