Miscellaneous. 335 
pairs of ‘the largest size commonly used, was arranged in the dome of the 
State House, and the carbon light and the photometric apparatus pre- 
pared for the purpose were placed in line across the same apartment, com- 
manding a range of about 50 feet. In view of the immense power of the 
light as observed in the previous experiment, I substituted for the 20-candle 
gas-burner, used at that time as the standard of comparison, a unit ten 
times as great, formed by the flame of a Kerosene lamp placed in the 
focus of a small parabolic reflector, and throwing its concentrated light on 
a photometric screen of prepared paper fixed in front of it, at the dis- 
tance of five feet. Before the observation the lamp and reflector were so 
adjusted as to make the light cast on the near side of the screen equiva- 
lent by measure to the action of 200 candles. A platform supporting the 
standard lamp and screen at the assigned distance was arranged to slide 
on a horizontal graduated bar, extending directly towards the carbon 
point, so that the screen should receive the rays from the electric light, 
and from the reflector perpendicularly on its opposite faces. In making 
the observations, the platform was moved to and fro until the illumina- 
tion on the opposite sides of the screen was judged to be equal, and then 
the measured distances of the two antagonising lights from the screen 
gave by easy computation their relative illuminating power. By a series 
of such observations it was found that the carbon light had a force varying 
from 52 to 61 times that of the lamp with reflector, making it equivalent 
in illuminating power to the action of from 10,000 to 12,000 standard 
sperm candles pouring their light from the same distance upon the surface 
of the screen. This it will be remembered is the effect of the unaided 
carbon-light sending its rays equally in all directions from the luminous 
centre, and falls vastly short of the illuminating force of the cone of col- 
lected rays which was seen stretching like the tail of a comet from the 
surface of the great reflector. Judging from some recent experiments on 
the power of such a reflector to augment the intensity of the light emanat- 
ing from its focus, there can be no doubt that along the axes of the cone 
when brought to its narrowest limits—the illuminating force of the carbou 
light'as displayed on the State House could be rivalled only by that of 
several millions of candles shining unitedly along the same line.” 
PUBLICATIONS RECEIVED. 
1. Sur la Statistique Générale des Différents Pays. Par M. Ad. 
Quetelet.—From the Author. 
2. Annuaire de l’Academie Royale des Sciences, des Lettres, et des 
Beaux Arts de Belgique, 1862-63.— From the Academy. 
3. Bulletin de PAcademie Royale des Sciences, des Lettres, et des 
Beaux Arts de Belgique, 30° Année, 2° Serie, tom. XI. et XII., 1861; 
32° Année, 2° Serie, tom. XV., Parts 1-6, et 32° Année, 2° Serie, 
tom. XVI., Part 7, 1863.—From the same. 
4. Proceedings of the Literary and Philosophical Society of Manchester. 
Nos. 11 ani 12, Session 1862-63.—From the Society. 
5. Proceedings of the Academy of Natural Sciences of Philadelphia, 
Nos. 7-12, for 1862; Nos. 1 and 2, for 1863.— From the Academy. 
