ON TERRESTRIAL MAGNETISM AND METEOROLOGY. 41 



of that body, dated Feb. 10, IS^l. Nor must your Committee pass in silence 

 the instructions given, and the instruments supplied by Government, (in du- 

 plicate, and with complete instructions for the use of each,) — also on applica- 

 tion from the President and Council of the Royal Society, — to the African 

 Expedition, for the purpose of observation in the course of that expedition. 

 From the scientific zeal which distinguishes many of the officers of that ex- 

 pedition, — scarcely inferior to that zeal in the cause of humanity which has 

 led them to enter on so perilous a service, — results highly valuable to mag- 

 netic science may be expected. The transportable magnetometer being one 

 of their instruments, observations on term-days during some months, corre- 

 sponding with those in Guiana, will probably be obtained, and thus localities, 

 otherwise of high interest, and remote from any central station, will be bound 

 together. 



Mr. Caldecott, Astronomer to His Highness the Rajah of Travancore, 

 whose magnetical observatorj^, completely furnished in instruments, com- 

 menced its operations on the May term-day of the present year, has also de- 

 clared his intention to undertake the magnetic survey of Southern India; 

 while in the north of that empire we may expect, from the zeal and energy 

 of Capt. Boileau, that no exertions on his part will be wanting to secure a 

 similar advantage in that quarter. 



In all such surveys it is highly desirable that a regular and concerted sy- 

 stem of observation should be followed, and above all things, that the con- 

 dition of exact conformity to the hours of simultaneous observation should 

 be adhered to ; as well as that, if practicable, all determinations of important 

 points, intended to be made with particular care and exactness, should be 

 performed on the term-days ; which object, by the exercise of a certain de- 

 gree of forethought in laying out the plan of travel, may doubtless be accom- 

 plished in the great majority of instances. 



Connected with, and of importance to, the practical working of the obser- 

 vatories, your Committee beg leave to call attention to Prof. Lloyd's supple- 

 mentary paper, " On the Mutual Action of permanent Magnets," in which 

 those conditions of equilibrium are investigated which it is possible to satisfy, 

 independent of the relative forces of the magnets. In this paper, independent 

 of the practical utility of the rules laid down for the disposal of the magnets 

 in fixed observatories, the demonstration of the extreme minuteness of the 

 possible amount of uncompensated error arising from mutual attraction can- 

 not but be regarded as highly satisfactory. 



Finally, your Committee have to report on their employment of the grant 

 of 50/., placed at their disposal at the last meeting, which they have expended 

 on the purchase of a transportable magnetometer, by Meyerstein, of Gottin- 

 gen, for the Guiana survey. Some improvements, not contemplated origin- 

 ally, having been introduced into the construction of this instrument, its total 

 cost, including freight, somewhat exceeded this sum, leaving a balance of 

 121. 2s. against the Committee, for which it is necessary they should pray an 

 indemnity, as well as a continuance of the grant of money placed at their 

 disposal. Signed, on the part of the Committee, 



J. F. W. Herschel. 



Reports of Committees appointed to provide Meteorological Instru- 

 ments for the use of M. Agassiz and Mr. M'Cord. 



With reference to the resolutions passed at Glasgow, viz. " That a Com- 

 mittee, consisting of Major Sabine and Sir J. Herschel, be requested to pro- 



