14th September, 1858.-The weather being too rough for distant work, we sent out the men to dredge in the Sound between the large Copeland and the Lighthouse Islands in 12 fathoms, and procured the following :

List of Crustacea inhabiting Belfast Bay. By Professor JOHN ROBERT KINAHAN, M.D., M.R.I.A. Explanatory marks: -D. Specimens obtained by me in 1858. C. In collections. C.S.B. Identified by C. Spence Bate, Esq.

This is made up from the following sources:-(1) Specimens obtained during dredging excursions at Bangor, Groomsport, Holywood, Carrickfergus, Whitehead, Blackhead, and the Gobbins; these species are marked D, and have been all carefully identified. (2) A careful examination of the specimens in the Belfast Museum, most of which are marked in the late Mr. W. Thompson's own hand; in the private collection of Mr. Geo. C. Hyndman; and some few which had been preserved by Edward Waller, Esq. (3) From the specimens obtained by the Ordnance Survey Collectors in 1837-38. And (4) as regards the Amphipoda, chiefly a list of the specimens collected by the late W. Thompson, Esq., and submitted to Mr. Westwood, kindly furnished to me by Charles Spence Bate, Esq., F.L.S., by whom they were identified. The list must be, however, looked on as a mere approximation to a full list of Crustacea, as many of the Amphipoda and Isopoda recorded even in Thompson's lists are purposely omitted, being critical species which have been so imperfectly described as to render their discrimination from kindred species hazardous in the extreme. I have therefore thought it more advisable to pretermit all notice of such species.

D. Inachus Dorynchus. Common at Grooms- D. Mysis chamæleon.

Description of new species of Crangon, C. Pattersonii, in foregoing list :Rostrum rounded, apex scarcely length of ocular peduncles; carapace with four (?) lines of spines; abdomen smooth, without sulcation, except in telson; in other respects as Crangon spinosus.

Additional List of Polyzoa. By the Rev. THOMAS HINCKS.

I have also met with the Asteroid Zoophyte, Sarcodictyon catenata of Forbes.

Appendix to Mr. VIGNOLES' paper "On the Adaptation of Suspension Bridges to sustain the passage of Railway Trains" (Rept. Brit. Assoc. 1857).

For calculations relating to Suspension Bridges, reduced to the simplest terms, and considering the curve of the chain as a parabola :

2y

w=minimum sectional area of the chain, exclusive of appendages.

n=appendages of the chain. (See explanations, a.)

w+n=sectional area of chain, for calculating its weight and tension.

u=weight of a cubic foot of iron.

e=maximum weight admitted on chain. (See explanations, b.)

a. Appendages of the Chains. The minimum sectional area of the chains is the product of the breadth and thickness of the iron thereof in its smallest dimensions. But the links of plate-chains overlap each other at their extremities, which are enlarged and connected together by screw-ended short bolts of large diameter, secured by nuts and keys; these additions to the simple chains constitute their appendages, and increase the weight (and consequently the average sectional area) by about from 20 to 25 per cent. of the minimum area. Where wire is employed for the suspension in the form of cables, the appendages thereof will bear a very much smaller proportion than the above to the minimum area, as they consist merely of the wrappings around the steel strands of the cables.

b. Maximum Weight admitted on the Chains. The maximum weight or strain on the chains or wire cables of suspension bridges, should not exceed a fourth or a fifth of the breaking weight or strain, nor should it exceed materially the half of that strain which would produce a permanent effect upon the natural elasticity of the iron. The breaking weight or strain of good wrought iron varies from 20 lbs. to as much as 28 lbs. (avoirdupois) upon the square inch of the section of the bar. The strain which causes wrought iron to take a permanent set (that is, which so stretches the fibres of the iron that their elasticity is injured, whereby the iron no longer returns to its normal length when the strain is taken off), varies from 10 lbs. to 14 lbs. per square inch. Consequently the expression (e) in the formula ought not to be taken higher than from 5 lbs. to 7 lbs., or from 0.0022 ton to 0.0032 ton.

c. Load on the Chain. This quantity comprises the weight of the sus pension rods (dependent from the chains or cables, and from which the platform of the bridge is suspended), also the weight of the roadway or platform, and the greatest weight with which the platform can be loaded. These, together, constitute the load on the chains, exclusive only of the weight of these chains themselves and of their appendages.

d. Dimensions of the Abutment. The height or depth of the abutment is to be measured from the point on the outer face thereof, at which the chains enter therein; and the length of the abutment is to be measured from that same point to the point at the opposite or inner side of the abutment to 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 subjected to be surrounded by water, either constantly or periodically, the consequent augmentation necessary in the dimensions and weight of the abutment 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 Committee, 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 conjunction 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