FEBRUARY 29, 1884.] 
demonstrations of the formula for the prismatoid, 
one section being made at will. Mr. Smith gave a 
new and simple demonstration of the ellipse of stress. 
— Mr. Magie gave a proof for the movement of 
liquids in capillary tubes, both cylindrical and coni- 
eal. Mr. M. MeNeill gave a method for reducing 
to the mean time of observation a series of microm- 
eter measures of distance and position angle, when 
one of the objects has such a large proper motion 
that these quantities do not vary proportionally with 
the time. 
Society of arts, Massachusetts institute of technology. 
Jan. 24.—Capt. D. A. Lyle, U.S.A., read a paper 
on the rise, progress, and methods of the U.S. life- 
saving service. The first organized attempt at saving 
life imperilled by wreckage was inaugurated by the 
Massachusetts humane society in 1782, but the true 
inception of the U.S, service was in 1848; and since 
that time, in spite of reverses, inadequate appropria- 
tions, etc., the service has steadily advanced in effi- 
ciency. It was established on its present enlarged 
_ basis in 1878, after several years of struggle. At 
present the whole number of stations is 189, of which 
139 are on the Atlantic coast. The following statis- 
tics for the year ending June 30, 1882, will show the 
efficiency of the service: disasters, 345; property in- 
volved, $4,766,000; property saved, $3,106,000; per- 
sons involved, 2,398, of whom all but 12 were saved; 
total expense, $594,889.74, or at the rate of less than 
$250 per person, without considering the value of 
property saved. During the more inclement months, 
dangerous shores are constantly patroled; and upon 
discovering a wreck, a projectile is fired over the 
vessel, carrying a line, by means of which the sailors 
draw out a cable, which they secure to the mast, and 
on which a life-car or a breeches-buoy is run back 
and forth, by which those on board are carried to the 
shore. Capt. Lyle explained all the details of the 
methods used, by means of a model. —— Mr. N. M. 
Lowe exhibited a model showing a method of trans- 
mitting power by belting, designed to replace the 
ordinary fast and loose pulley. 
Academy of natural sciences, Philadelphia. 
Jan. 15.— Prof. H. C. Lewis exhibited a speci- 
men of limestone from Utah which emitted a lurid 
red light when struck, scratched, or heated. The 
glow lasted from half a second, when lightly struck, 
to a much longer time as the result of a blow. On 
examination, the specimen proved to be an almost 
perfectly pure carbonate of lime, with but a slight 
percentage of impurities. It is loose-grained, white, 
and crystalline, the grains being but slightly coherent, 
thus giving the rock the appearance of a soft sand- 
stone. It crumbles easily between the fingers, form- 
ing a coarse sand. When heated in a glass tube over 
a flame, it glows with a deep red light, which lasts for 
a minute or moreafter withdrawing the flame. After 
two or three heatings the phosphorescent property 
disappears. A search through the collection of the 
academy for limestones having similar properties re- 
sulted in finding specimens from Kaghberry, India, 
which glowed with a strong yellow phosphorescence 
SCIENCE. 
267 
when heated, although no such effect was produced 
by seratching or striking. It was of great interest to 
find that the Indian limestone alone, of all in the col- 
lection, had the precise external characters of that 
from Utah. This similarity is more than a coinci- 
dence. It confirms Becquerel’s view that phospho- 
rescence depends upon physical rather than chemical 
conditions. In the rocks referred to, it is probably 
dependent upon a disturbance of their loosely aggre- 
gated crystalline particles, whether such be produced 
by percussion, friction, heat, or decrepitation. 
Dr. J. Leidy communicated the results of a recent 
trip made to Atlantic City for the purpose of collect- 
ing and studying some of the life-forms thrown up on 
the beach by the storm of Jan. 8. The shore at the 
highest line reached by the tide was for miles covered 
with millions of bushels of the common beach-clam, 
Mactra solidissima. In many places they were closely 
packed together in extensive patches. Besides those 
visible, it is probable that at least as many more were 
covered by the sand thrown up at the same time, or 
had buried themselves in the beach. Until this evi- 
dence of the storm he had no suspicion that the 
mollusk was so exceedingly abundant on the coast; 
though he had been well aware that it was very com- 
mon, having repeatedly seen large quantities thrown 
on shore under similar circumstances. With the 
Mactra were other mollusks, which, although nu- 
merous enough, appeared to be few, compared to the 
former. These were Fulgur carica, and F. canalicu- 
lata, Natica heros, N. duplicata, and N. obsoleta. 
Hermit crabs were also abundant, — Eupagurus polli- 
caris in the shells of Natica and Fulgur, and E. 
longicarpus in shells of Natica. Spider-crabs were 
common, and a few half-grown horseshoe-crabs were 
also observed. Some bunches of the common edible 
mussels were collected. 
It seemed remarkable, on the other hand, that 
some of the commonest mollusks were conspicuous 
by their absence; few or no oysters, clams (Venus 
mercenaria), squirt-clams, or horse-mussels, having 
been seen. Scarcely any traces of annelids were ob- 
served, except masses of dead Serpula. There were 
also no echinoderms, except one, Caudina arenata, 
which occurred at some places in considerable num- 
bers. It was believed that this was the first time the 
animal had been observed on the coast of New Jersey. 
They usually range from three to four inches in 
length, but several were found upward of six inches, 
and over an inch in diameter at the thicker portion 
of the body. ‘They present but little resemblance to 
the forms commonly recognized as echinoderms or 
sea-urchins, looking much like large fleshy worms. 
Dissection, however, at once reveals their true rela- 
tionship. 
It is an interesting question as to what becomes of 
the vast quantity of Mactra and other shells inces- 
santly cast on shore. Storms annually oblige the 
ocean to contribute, from its inexhaustible stores, 
multitudes of mollusks and other animals to the 
sandy beach. By exposure to the influence of the 
weather, the air, the sun, the rain, frosts, and other 
destructive influences, the calcareous shells are broken 
