366 



BRITISH ASSOCIATION FOR THE ADVANCEMENT OP SCIENCE. 



[1855. 



pinna; of a fern, or a few fragments of the stems of Ulodendron or 

 Sigillaria, give every inadequate ideas of tlie plants to which they had 

 belonged in their state of original entireness. 



Ei:perinipnlal Observations on an Electric Cable, by Mr. Wildjian 

 Whitehouse. — After referring to the rapid progress in submarine te- 

 legraphy which the last four years have witnessed, Mr. Whitehouse 

 said that he regarded it as an established fact that the nautical and 

 engineering difficulties which at first existed had been already over- 

 come, and that the experience gained in submerging the shorter 

 lengths had enabled the projectors to provide for all contingencies af- 

 fecting the greater. The author then drew the attention of the Section 

 to a series of experimental observations which he had recently made 

 upon the Mediterranean and Newfoundland cables, before they sailed 

 for their respective destinations. These cables contained an aggregate 

 of 1,125 miles of insulated electric wire, — and the experiments were 

 conducted chiefly with reference to the problem of the practicability of 

 establishing electric communications with India, Australia, and Ame- 

 rica. The results of all the experiments were recorded by a steel 

 style upon electro-chemical paper by the action of the current itself, 

 while tlie paper was at the same time divided into seconds and frac- 

 tional parts of a second by the use of a pendulum. This mode of 

 operating admits of great delicacy in the determination of the results, 

 as the seconds can afterwards be divided into hundredths by the use 

 of a "vernier," and the result read oif with the same facility as a 

 barometric observation. Enlarged fac-similes of the electric autographs, 

 as the author calls them, were exhibited as diagrams, and the actual 

 slips of electro-chemical paper were laid upon the table. The well- 

 kuown effects of induction upon the current were accur.ately displayed ; 

 and contrasted with these were other autographs showing the effect of 

 forcibly discharging the wire by giving it an adequate charge of the 

 opposite electricity in the mode proposed by the author. No less 

 than eight currents — four positive and four negative — were in this way 

 transmitted in a single second of time through the same length of 

 wire (1,1"25 miles) through which a single current required a second 

 and a half to discharge itself spontaneously upon the paper. Having 

 stated the precautions adopted to guard against error in the observa- 

 tions, the details of the experiments were then concisely given, includ- 

 ing those for "velocity," which showed a much higher rate attainable 

 by the magneto-electric than by the voltaic current. The author then 

 recapitulated the facts, to which he specially invited attention : — First, 

 the mode of testing velocity by the use of a voltaic current divided 

 into two parts (a split current), one of which shall pass through a 

 graduated resistance tube of distilled water, and a few feet only of 

 wire, while the other part shall be sent through the long circuit, both 

 being made to record themselves by adjacent styles upon the same 

 slip of electro-chemical paper. Second, the use of magneto-electric 

 " twin-currents," synchronous in their origin, but wholly distinct in 

 their metallic circuits, for the same purpose, whether they be made to 

 record themselves direct upon the paper, or to actuate relays or re- 

 ceiving instruments which shall give contacts for a local printing bat- 

 tery. Third, the effects of induction, retardation of the current, and 

 charging of the wire, as shown autographically ; and contrasted with 

 this — fourth, the rapid and forcible discharging of the wire by the use 

 of an opposite current ; and hence — fifth, the use of this as a means of 

 maintaining, or restoring at pleasure, the electric equilibrium of the 

 wire. Sixth, absolute neutralization of currents by too rapid reversal. 

 Seventh, comparison of worliing speed attainable in a given length of 

 wire by the use of repetitions of similar voltaic currents as contrasted 

 with alternating magneto-electric currents, and which, at the lowest 

 estimate, seemed to be seven or eight to one in favour of the latter. 

 Eighth, proof of the co-existence of several waves of electric force of 

 opposite character in a wire of given length, of which each respectively 

 will arrive at its destination without interference. Ninth, the velocity, 

 or rather amount of retardation, greatly influenced by the energy of 

 the current employed, other conditions remaining the same. Tenth, 

 no adequate advantages obtained in a 300-mile length by doubling or 

 trebling the mass of conducting metals. The author, in conclusion, 

 stated his conviction that it appeared from these experiments, as well 

 as from trials which he had made with an instrument of the simplest 

 form, actuated by magneto-electric currents, that the working speed 

 attainable in a submarine wire of 1,125 miles was ample for commer- 

 cial_ success. And may we not, he added, fairly conclude also that 

 India, Australia, and America, are accessible by telegraph without the 

 use of wires larger than those commonly employed in submarines 

 cables ? 



Remarks on the Chronology of iJie Formations of the Moon, by Prof. 

 NiCHOL.— Prof Nichol stated that, through the munificence of the 



Marquis of Breadalbane, he had been enabled to bring to bear on the 

 delicate inquiries, whose commencement he intended to explain, a very 

 great if not a fully adequate amount of telescopic power. A speculum 

 of twenty-one inches, originally made by the late Mr. Ramage with 

 the impracticable focal length of fifty-five feet, had, at the expense of 

 that noble Lord, been re-ground, polished, mounted as an equatoreal, 

 and placed in the Glasgow Observatory, in its best state only about 

 six weeks ago. Prof. Nichol showed some lunar photographs, which 

 indicated the great light with which the telescope endowed its focal 

 images, and entered on other details as to its definition. The object of 

 the present paper is the reverse of speculative. It aims to recall 

 from mere speculation, to the road towards positive inquiry, all ob- 

 servers of the lunar surface. To our satellite hitherto those very ideas 

 have been applied, which confused the whole early epochs of our ter- 

 restrial geology, the notion, viz., that its surface is a chaos, the result 

 of primary, sudden, short-lived and lawless convulsion. We do not 

 now connect the conception of irregularity with the history of the 

 earth : — it is the triumph of science to have analyzed that apparent 

 chaos, and discerned order through it all. The mode by which this 

 has been accomplished, it is well known, has been the arrangement of 

 our terrene mountains according to their relation to time : their rela- 

 tive ages determined, the course of our world seemed smooth and 

 harmonious, like the advance of any other great organization. Ought 

 we not then to attempt to apply a similar mode of classification to the 

 formations in the moon, — hoping to discern there also a course of de- 

 velopment, and no confusion of manifestation of irregular convulsion ? 

 Prof. Nichol then attempted to point out that there appeared a practi- 

 cal and positive mode by which such classification might be effected. 

 It could not, in so far as he yet had discerned, be accomplished by 

 tracing, as we had done on earth, relations between lunar upheavals 

 and stratified rocks ; but another principle was quite as decisive in 

 the information it gave, viz., the intersection of dislocations. There 

 are clear marks of dislocation in the moon — nay, the surface of our 

 satellite is overspread with them. These are the rays of light, or 

 rather bright rays, that flow from almost all the great craters as their 

 centres, and are also found where craters do not at present appear. 

 Whatever the substance of this highly reflecting matter, it is evidently 

 no superficial layer or stream, like lava, but extends downwards a 

 considerable depth into the body of the moon. In short, we have no 

 likeness to it on earth, in the sense now spoken of, except our great 

 trap and crystalline dykes. It seemed clear, then, that the intersection 

 of these rays are really intersections of dislocations, from which we 

 might deduce their chronology. Can the intersection, however, be 

 suificiently seen ? — in other words, is the telescope adequate to deter- 

 mine which of the two intersecting lines has disturbed or cut through 

 the other? Prof. Michol maintained the affirmative in many cases, 

 and by aid of diagrams, taken down from direct observation, illustra- 

 ted and enforced his views. 



JVote on Solar Refraction, by Prof. Piazzi Smyth. — Amongst other 

 interesting and important consequences of the dynamical theory of 

 heat, Prof. W. Thomson having deduced the necessity of a resisting 

 medium, the condensation of this about the sun, and a consequent re- 

 fraction of the stars seen in that neighbourhood. Prof. Piazzi Smyth 

 had endeavoured to ascertain by direct astronomical observation 

 whether any such effect was sensible to our best instruments. Owing 

 to atmospheric obstructions, only three observations, yielding two re- 

 sults, had been yet obtained ; but both these indicated a sensible 

 amount of solar refraction. Should this effect be confirmed by more 

 numerous observations, it must have important bearings on every 

 branch of astronomy; and as the atmosphere at all ordinary observa- 

 tories presents almost insuperable obstacles, the author pointed out 

 the advantage of stationing a telescope for this purpose on the summit 

 of a high mountain. 



Erk.atum. — The Lithographer of the Map of the Township of Col- 

 chester, which accompanied the conclusion of Major Lachlan's paper 

 in the last number of the Journal, has introduced an error in the 

 direction of one of the Canoe Canals, which we take this opportunity 

 of rectifying. Instead of running straight through Round Marsh and 

 Long Marsh, it should run due north along the borders of Long Marsh 

 as far as the 8th Concession, and then across Roach's Marsh only, 

 until it approached the River Canard. A drain from Round Jlarsh 

 into the Canoe Canal will accomplish all that is required with respect 

 to the drainage of Round Margh. 



