MAGNETIC AND METEOROLOGICAL OBSERVATORIES. 295 
which the chains extend, and where they are attached or fastened by means 
of mooring-plates, abutting against this extreme end. The weight of the 
abutment will be calculated from its dimensions, in proportion to the specific 
gravity of the material employed in its construction ; and the actual weight 
of the abutment, as built, should be from four to five times the theoretical 
weight, determined by the formula, as that required to resist the tension, 
exclusive of friction or surface-resistance. If the abutment should be sub- 
jected to be surrounded by water, either constantly or periodically, the con- 
sequent augmentation necessary in the dimensions and weight of the abut- 
ment must be determined, in proportion to the depth of water in which it 
may be submerged. 
Report of the Joint Committee of the Royal Society and the British 
Association, for procuring a continuance of the Magnetic and 
Meteorological Observatories. 
At the Meeting of the British Association, which was held at Dublin in 
August 1857, a resolution was adopted, proposing the continuance of the 
system of magnetical observations which was commenced under the auspices 
of the Royal Society and of the British Association in 1840; and a Com- 
mittee, consisting of the President of the Association, the Rev. Dr. Robinson, 
and Major-General Sabine, was appointed, to request the cooperation of the 
President and Council of the Royal Society in the endeavour to attain this 
object, and to take, in conjunction with them, such steps as may appear 
desirable for that end. — 
The Committee thus appointed accordingly held a meeting in London, on 
the 5th November last, at which it was agreed to recommend that hourly 
observations, for not more than five years, should be undertaken at certain 
stations in the British Colonies ; and a letter was addressed to the President 
of the Royal Society, asking for his cooperation, and that of the Council of 
the Society, in endeavouring to attain that object. 
This application was favourably received by the Council of the Royal 
Society ; and on the 10th of December, 1857, the following resolution was 
adopted in reference to it:— 
“That Sir John Herschel, the Astronomer Royal, the Dean of Ely, and 
Dr. Whewell, be appointed a Committee, to cooperate with the Committee 
appointed with this view by the British Association, and to take, in conjunc- 
tion with them, such steps as may be necessary, including, if it be thought 
desirable, an application to the Government.” 
In consequence of this resolution, a correspondence took place among the 
members of the two Committees, which having resulted, it is believed, in a 
general agreement as to the course to be adopted, the joint Committee so 
acting in cooperation met at Leeds on the 24th September, and in the first 
instance proceeded to inquire into the nature and scientific value of the results 
which have already been secured by the system of observation hitherto 
carried out, at the observatories maintained by the Government, at the joint 
recommendation of these two bodies; with a view to forming a distinct opinion 
whether they are such as to merit being regarded as a reasonable, and, what 
may be called, a remunerative return for the labour and thought bestowed 
upon them, and the very considerable expenditure of the public money 
incurred by them. In so doing, they have limited their views to the results, 
as.compared with the expenditure, in the British Colonial magnetic observa- 
