Rev. W. R. Dawes on an Equatorial. 421 
. At the Librarie centrale des sciences rue de Seine; Recherches sur le non-homogé- 
j j M. du M 
ntité de (étincelle dinduction, par M. Ts, pu Moncet, 1860,—M. oncel, who 
hee his leisure to the study of electricity and its applications, presents in this 
ure the result of his researches upon the electric spark, and especially the 
spark of induction, of which the non-homogeneity was discovered by him in 1855, 
At Bailliére Bros., Paris & raité dlementaire de Physique expérimen- 
tale, Tom.:1 F r M, For , professor of Physics at the Lyc i 
rk, even by the confession of the author, contains nothing ne 
Nancy.—T: y 
but is distinguished by its method. The most difficult questions in regard to gravity, 
= atics and heat are explained in the i 
rendered intelligible to persons little versed in these matters, which are so i 
verte. 
par Victor Meunier. 8°, 1860—This work appears by numbers, once a week ; its 
author, of whom we have often spoken, has acquired in France a great reputation 
. 
Arr. XXXVIIL.— Description of an Equatorial recently erected at 
Hopfield Observatory, Haddenham, Bucks ; by the Rey. W. R. 
AWES. 
(From the Monthly Notices of the Royal Astronomical Society.) 
_My observatory was furnished, in May last, with an equatori- 
ally-mounted telescope by Messrs. Alvan Clark and Sons, 0 
“Boston, U 
The form combines great firmness and compactness with 
considerable elegance of design. ‘The massive part of its struc- 
lure is of cast-iron, the base of which is firmly-bolted down to a 
stone pier. The semicircular form of the upper part affords a 
Secure position for most of the wheel-work of the driving-clock, 
of which the going-weight descends in a groove on the east side 
> Rigas pier, and is not seen in the drawing. The space between 
he polar axis and the semicircular bed-piece 1s occupied at its 
lower part by the hour-circle. Immediately ne this is a 
Clock occupies the upper portion. "Mhe sector has a radius of 
ight ascension. This arc has a face of an inch and. a half in 
breadth, between which and a cylinder 7 inches in cireumference 
These bands are both keyed by the end into one groove in the 
cylinder, at such a distance that they cannot overlap or interfere 
with each other. They are then bent round the cylinder in 
