22 SEVENTH REPORT—1837. 
means. With this apparatus it is intended to make observations of 
the absolute variation twice each day, as is done in the observatory of 
Professor Gauss, of Gottingen,—the course of the diwrnal variation, 
and the hours of maxima and minima, having been ascertained by a 
series of preliminary observations with the same instrument. <A 
similar instrument, in a form somewhat modified, will serve for the 
observation of the diurnal changes of the horizontal force. 
An apparatus, constructed by M. Gambey, and similar to the one 
made by that artist for M. Kupffer, will be used in observing the 
diurnal variations of the dip. Gauss’s large apparatus will also be 
set up in the same room, and will be used occasionally, especially in 
observations of the absolute intensity, made according to the method 
proposed by that distinguished philosopher. The bars are too large 
to be employed in conjunction with other magnetical apparatus. 
It is intended to combine a regular series of meteorological obser- 
vations, with those on the direction and intensity of the terrestrial mag- 
netic force just spoken of; and every care and precaution has been 
adopted in the construction of the instruments. 
In conclusion, Mr. Lloyd said, that he felt it a duty to allude to the 
liberality and zeal in the cause of science which had been evinced by 
the Board of Trinity College on this occasion. The probable expense 
of the building and instruments is estimated at 1000/.; and that sum 
was immediately allocated to the purpose, when it appeared that the 
interests of science were likely to be benefited by the outlay. 
Notice of Electrical Researches by Proressor Henry, 
of Princeton, U.S. 
The primary object of these investigations was to detect, if possible, 
an inductive action in common electricity, analogous to that discovered 
in a current of galvanism. For this purpose an analysis was instituted 
of the phenomena known in, ordinary electricity by the name of the 
lateral discharge. Professor Henry was induced to commence with 
this from some remarks by Dr. Roget on the subject. The method of 
studying the lateral spark consisted in catching it on the knob of a 
small Leyden phial, and presenting this to an electrometer. The 
result of the analysis was in accordance with an opinion of Biot,—that 
the lateral discharge is due only to the escape of the small quantity 
of redundant electricity which always exists on one or the other side of 
a jar, and not to the whole discharge. The Professor then stated 
several consequences which would flow from this; namely, that we 
could increase or diminish the lateral action, by the several means 
which would affect the quantity of redundant, or, as it may be called, 
free electricity, such as an increase of the thickness of the glass, or by 
substituting for the small knob of the jar a large ball. But the ar- 
rangement which produces the greatest effect, is that of a long fine 
copper wire insulated, parallel to the horizon, and terminated at each 
end by a small ball. When sparks are thrown on this from a globe 
of about a foot in diameter, the wire, at each.discharge, becomes 
