British Association for the Advancement os if 113 
ductors of electricity, and freely connected ef “efficient % 1 
tors with the sea, the electrical agency would have an ‘unli 
and easy source of diffusion in all directions, and hence the ship 
would be safe from the moment the flash struck the mast head. _ 
From his inquiries it appeared that in 100 cases of. ships in the 
British Navy struck by lightning, the number struck on the 
main-mast were to those struck on the fore-mast as 2: 1; to those 
struck on the mizen-mast, as 10: 1; to those struck on the bow- 
sprit, as 50: 1. About one ship in six is set on fire in some part 
of the hull, sails or rigging. In one half the cases some of the 
crew were either killed or wounded. In the 100 cases alluded 
to, 62 seamen were killed, and about 114 wounded. These are 
exclusive of one case of a frigate, in which nearly all the crew 
perished, and of 12 eases in which the numbers killed or wound-— 
_ ed were set down in the accounts given as several or many. In 
these 100 cases, there were damaged or destroyed 93 lower 
masts, principally of line-of-battle ships and frigates, 83 top- 
masts, and 60 topgallant-masts. 
A notice was read, from Dr. Robinson, on the determination 
of the are of longitude between the observatories of Armagh and 
Dublin. In September, 1838, Mr. Dent, by means of twelve 
chronometers, determined the longitude of Dublin to be +-25m. 
21.08s., longitude of Armagh +26m. 35.44s. Subsequently, by 
means of rocket-signals, Dr. R. found the difference between 
Armagh and Dublin to be Im. 14.258s. or .1s. less than the chro- 
_  fometrical determination. ss 
-_ ~ The Longitude of New York City Hali was determined by — 
Mr. E. J. Dent, by means of chronometers sent out by the 
British Queen, in July, 1839, to be +4h. 56m. 3.55s. which va- 
ties less than 3s. from the previously received determination. 
(See this Journal, vol. xxxvii, p. 400. 
Prof. Whewell made some remarks on Dr. Wollaston’s argu- 
ment on the question of the infinite divisibility of matter, drawn 
from the finite extent of the atmosphere. Dr. W. imagined that 
if the extent of the earth’s atmosphere be finite, air must consist 
of indivisible atoms, since he assumed that the only way in 
Which we can conceive an upper surface of the atmosphere, is by 
Supposing an upper stratum of atoms, the weight of which, 
acting downwards, is balanced by the repulsive force of the in- 
ferior strata acting upwards. Prof. W. contended that such a» 
Vol. xxxvint, No. 1.—Oct.-Dec. 1839. 15 _ 
