- 
98 Influence of the Moon on Declination of the Magnetic Needle. 
half broad, by the latter, ten miles long by three wide. And — 
both were seen by a large number of persons. 
ince my memoir on meteorites was presented to the American 
Association for the Advancement of Science, and published, I 
have collected several important physical and chemical data that 
cannot be overlooked in the study of the nature and origin of — 
these bodies. I will merely enumerate some of them now; Tre- 
serving for a future occasion the proof upon which they are based _ 
and the deductions that may be drawn from them. Ist. The — 
light emitted from meteoric stones does not arise from incandes- 
cence, but from electricity or some other cause. 2nd. That the 
noise attending their fall is not that arising from the explosion 
of a solid, but that it is by concussion of the atmosphere arising 
from the rapid motion of the body through it or in part due to 
electric discharge. . 
d. t meteoric showers are not the results of fragments 
from the rupture of one solid body, but the separation of small 
and distinct aerolites that have entered our atmosphere in groups. | 
4th. That the black coating is not of atmospheric origin, but is _ 
already formed when these bodies enter our atmosphere. : 
would also call the attention of those engaged in the exami: _ 
nation of this class of bodies to the study of the true nature of their 
black coating, also to the fact that observers at a distance often 
see these bodies in a luminous state, while those situated where — 
they fall, do not observe this luminosity. 
liisletnsmansicausesitill: 
Arr, XIL— Abstract of a Discussion of the Influence of the Moon 
on the Declination of the Magnetic Needle, from the observations 
at the Girard College, Philadelphia, between the years 1840 and 
— by A. D. BAcuE, Superintendent United States Coast — 
urvey. : 
of the secular change, and of the annual variation may be sev" 
erally eliminated, leaving residuals from which the lunar influ — 
ence is to be studied. - 
ach observation was marked with its corresponding lunat 
hour and the hourly normals used for comparison. This method 
