PROVISIONAL REPORTS, AND NOTICES. 431 
struments, and facilitating, by constant attention and activity, 
those innumerable details which are involved in a combination 
so extensive,—a combination which, but for those exertions, 
your Committee are fully of opinion, must have been greatly 
wanting in that unity of design and cooperation which now so 
eminently characterizes it. 
Signed, on the part of the Committee, 
J. F. W. Herscue. 
Referring to the magnetical observatory at Breslau, men- 
tioned in this report, Masor SaBine read the following letter 
from its director, M. von Boguslawski, received since the 
meeting had commenced. 
Breslau, September 7, 1840. 
My pear Sir,—I have the pleasure to inform you, that during the last 
magnetic term, viz. on the 28th and 29th August, I have made observations 
with the two magnetic instruments provided by the British Association. Not- 
withstanding the Michaelmas Term of our University has began, I have suc- 
ceeded in engaging and instructing a double number of observers sufficient to 
place them at the declination magnetometer in the magnetic cabinet, as well as 
at the horizontal, and at the vertical-force magnetometers in the great room of 
the observatory. The observations hitherto made can, however, only be con- 
sidered as observations of the magnetic variations, because there are several 
masses of iron fixed in the buildings. The prospect of obtaining a separate 
magnetic observatory being still distant, I feel myself highly indebted to Pro- 
fessor Lloyd for the assistance his paper ‘“‘ On the Mutual Action of Permanent 
Magnets, &c.” has afforded me. By these instructions I have succeeded in 
effecting what at first seemed to be impossible, namely, to place the declination 
magnetometer, the bifilar instrument, and the vertical-foree magnetometer, in the 
same room of the present magnetic cabinet, and to put them in equilibrium. How 
this is to be done by three small fixed subsidiary magnetic bars, I shall here- 
after explain to Professor Lloyd; and if he agrees with me, all three instru- 
ments will be placed in the magnetic cabinet at the next term. 
However, I shall use for a declination magnetometer the second magnetic 
bar received with the horizontal:force magnetometer, instead of the present bar 
of four pounds, in order to obtain small correction-constants. I shall then ex- 
pect with patience the establishment of a proper magnetic observatory, so as to 
begin to make absolute and daily observations. Please to communicate this in 
my name to the meeting of the British Association at Glasgow ; and have the 
kindness to express to them my regret, that on account of the necessary ar- 
rangements I have to make, I am prevented from accepting their honourable in- 
vitation, and assisting at their instructive assembly. 
(Signed) Henry von Bocustawskl, 
Major Edward Sabine. 
Major Sabine also presented to the Section, at the request 
of M. Kupffer, Director-general of the magnetical observatories 
of Russia, several copies of a report addressed by that gentle- 
man to the Imperial Academy of Sciences at St. Petersburg, 
entitled, “‘ Sur les Observatoires Magnétiques fondés par ordre 
des Gouvernemens d’Angleterre et de Russie, sur plusieurs 
