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96 British Association for the Advancement of Science. 
rora Borealis, and to record every phenomenon of this nature; 
and I have no doubt, from the lists already sent me, that this 
class of observations will be the most complete and valuable that 
have ever been made.” Accompanying this report were tables 
of hourly observations of the barometer and thermometer (made 
at Kingussie, 700 or 800 feet above sea level, by Mr. Rutherford) 
during the 27th, 28th, 29th, and part of the 30th of November, 
1838; the barometer having gradually sunk down to the lowest, 
_ 27.200, on the 29th at 3 P. M., and risen again rapidly to its usual 
height after 9 A. M. of the 30th. There were also accounts of 
three occurrences of the Aurora Borealis, viz. on the 13th and 
17th of November and 14th of December, 1838. 
A paper was read On the best positions of three magnets, im 
reference to their mutual action, by Rev. H. Lloyd. It is a prob- 
lem of much importance, in the arrangement of a magnetical ob- 
servatory, to determine the relative position of the magnetical in- 
struments in such a manner, that their mutual action may be el- 
ther absolutely null, or at least readily calculable. Such the 
author stated to be the object of the present investigation. ~ The 
problem may be reduced to this; to determine the position of the 
three magnets A, B, and C, in such a manner, that the resultant 
actions exerted upon A and B, respectively, by the other two, 
shall lie in the magnetic meridian. _ The solution of this problem 
was shown to be contained in two equations, which may, of 
course, be satisfied by means of two unknown angles; so that 
when we have a greater number of undetermined quantities, some 
of them remain arbitrary, and the conditions may be fulfilled in 
various ways. In reply to a question from the President, Mr. 
Lloyd briefly explained the arrangement of the portable observa- 
tory, adopted by Capt. J. Ross, in his preparations for the Antare- 
tic Expedition. It is so constructed as to form either three small 
separate rooms, or one large one. The former arrangement is de- 
sirable at places where the dip is nearly 90°, and where, conse- 
quently, the horizontal directive force is very small, and the dis- 
turbing action of the magnets on one another, relatively great. 
The parts are connected with copper fastenings ; and the whole 
is so arranged, as to occupy a very small bulk when in pieces, and 
to be capable of being put together with quickness and secutity- 
New Photometer. Prof. Daubeny exhibited the model of a0 
apparatus, by means of which, in a more complete condition, he 
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