66 



NA TURE 



[May 17, 1883 



I 



We suspect that thi; statement has arisen from a misconception 

 of Kiell's words, while referring to the star in his Introduction 

 to the true Astronomy or Astronomical Lectures t &c, the first 

 English edition of which appears to have been published in 1721. 

 In the third edition, 1739 (which is before us), at p. 56, we 

 read, after his reference to the phenomena in 1572, " Leovitius, 

 from the history of those times, tells us that in the time of the 

 Emperor Otho, about the year 945, a new star appeared in 

 Cassiopeia, just such a one as was seen in his time in the year 

 1572. And he brings us another ancient observation — that there 

 was likewise seen in the northern region of the heavens, near the 

 constellation Cassiopeia, in the year 1264, an eminently bright 

 star, which kept itself in the same place, and had no proper 

 motion. It is probable that these two stars might have been the 

 same with that which was seen by Tyeho, and that in about 150 

 years the same star may again make its appearance." 



It will be remarked that Kiell makes no reference to a >y star 

 seen midway between 945 and 1264, nor between 1264 and 1556, 

 and it seems his meaning is clear, that Tycho's star, with a 

 period of some 300 years, might make its appearance again "in 

 about 150 years " from the time at which he wrote, as it might 

 do were its changes accomplished in about three centuries. The 

 misinterpretation of Kiell's words has led to his being credited 

 with the opinion that the period is about 150 years, an idea 

 which he probably never intended to express 



ELECTRICITY APPLIED TO EXPLOSIVE 

 PURPOSES ' 



N introducing the subject the lecturer indicated the principal 

 advantage; which it had been early observed would result 

 from a certain mode of firing explosive charges by electric cur- 

 rent instead of by the ordinary fuzes, the best of which had in- 

 herent defects, greatly limiting their use for any but the simplet 

 operations. He traced the history and development of electric 

 firing from the crude experiments of Benjamin Franklin, about 

 the year 1 75 1, through the various stages in which frictional 

 electricity, volta- induction apparatus, and magnetoelectric ma- 

 chines had supplied the means of generaiing the current, the 

 tendency of late years being to revert to a modified form of 

 voltaic battery for one class of work, and to employ dynamo- 

 electric machines for another class. The history and develop- 

 ment of the low-tension or wire fuze, and of the various fuzes 

 employed with electiic currents of high tension, were also dis- 

 cussed, and their relative advantages, defects, and performances 

 were described. 



The only sources of electricity which at present thoroughly 

 fulfilled the conditions essential in the exploding-agent for sub- 

 marine mines v ere constant voltaic batteries. They were simple 

 of construction, com| aratively inexpensive, required but little 

 skill or labour in their production and repair, and very little 

 attention to keep them in constant good working order for long 

 periods, and their action might be made quite independent of 

 any operation to be performed at the last moment. 



When first arrangements were devised for the application of 

 electricity in the naval service to the firing of guns and so-called 

 outrigger charges, the voltaic pile recommended itself for its 

 simplicity, the readiness with which it could be put together and 

 kept in order by sailors, and the considerable power presented 

 and maintained by it for a number of hours. Different forms 

 of pile were devised at Woolwich for boat and ship use, the 

 latter being of sufficient power to fire heavy broadsides by 

 branch circuits, and to continue in a serviceable condition for 

 twenty-four hours, w hen they could be replaced by fresh bat- 

 teries, which had in the meantime been cleaned and built up by 

 sailors. 



The Daniell and sand batteries first used in conjunction with 

 the high-tension fuze for submarine mining service were speedily 

 replaced by a modification of the battery known as Walker's, 

 which was after some time converted into a modified form of the 

 Leclanche battery. 



1 he importance of being able to ascertain by tests that the 

 circuits leading to a mine, as well as the fuzes introduced into 

 that circuit, were in proper order, very soon became manifest ; 

 and many instances were on record in the earlier days of sub- 

 marine mining of the disappointing results attending" the acci- 

 dental disturbance of electric firing arrangements, when proper 



1 The fifth of the series of Six Lectures on the Applications of Electricity, 

 delivered on Thursday evening. April 19, at the Institution of Civil 

 Engineers, by Sir F. A. Abel, F.R.S., Hon. M.Inst. C.E. 



means had not been known or provided for ascertaining whether 

 the circuit was complete, or for localising any defect when dis- 

 covered. 



The testing of the Abel fuze, in which the bridge, or igniting 

 and conducting composition, was a mixture of the copper 

 phosphide and sulphide with potassium chlorate, was easy of 

 accomplishment (by means of feeble currents of high tension), 

 in proportion as the sulphide of copper predominated over the 

 phosphide. Even the mo^t sensitive might be thus tested with 

 safety ; but when the necessity for repeated testing, or even for 

 the passing of a signal through the fuze, arose, as in a permanent 

 system of submarine mines, the case was different, this fuze being 

 susceptible of considerable alterations in conductivity on being 

 frequently submitted to even very feeble test-curre its, and its 

 accidental ignition by such comparatively powerful test- or signal- 

 currents as nvght have to be employed, became so far possible 

 as to create an uncertainty which was most undesirable. 



Hence, and also because the priming in these fuzes was liable 

 to some chemical change detrimental to its sensitiveness, unless 

 thoroughly protected from excess of moisture, another form ot 

 high-tension fuze, specially adapted for submarine mining service, 

 was devised at Woolwich. This, though much less sensitive 

 than the original Abel fuze, was sufficiently so for service 

 requirements, while it presented great superiority over the latter 

 in stability and uniformity of electric resis'ance ; and, though 

 not altogether unaffected by the long-continued transmission of 

 test-currents through it, the efficiency of the fuze was not 

 affected thereby. 



Although high-tension fuzes presented decided advantages in 

 point of convenience and efficiency over the earlier form of 

 platinum wire fuze, the requirements which arose, in elaborating 

 thoroughly efficient permanent systems of defence by submarine 

 mines, and the demand for a battery for use in ships which 

 would remain practically constant for long periods, caused a 

 very careful consideration of the relative advantages of the high- 

 and low-tension systems of firing to result in favour of the em- 

 ployment of wire fuzes for these services. In addition to the 

 disadvantages pointed out there was an element of uncertainty, 

 or possible danger, in the employment of high-tension fuzes, 

 which, though partly eliminated by the adoption of voltaic 

 batteries, in place of generators of high-tension electricity, 

 might still occasionally constitute a source of danger, namely, 

 the possibility of high-ten-ion fuzes being accidentally exploded 

 by currents induced in cables, with which they were connected, 

 during the occurrence of thunderstorms, or of less violent 

 atmospheric electrical disturbances. 



Experiment, and the results obtained in military service- 

 operations, had demonstrated that if insulated wires, immersed 

 in water, buried in the earth, or even extended on the ground, 

 were in sufficient proximity to one another, each cable being in 

 circuit with a high-tension fuze and the earth, the explosion of 

 any of the fuzes by a charge from a Leyden jar, or from a 

 dynamo-electric machine of considerable power, might be 

 attended by the simultaneous ignition of fuzes attached to 

 adjacent cables, which were not connected w ith the source of 

 electricity, but which become sufficiently charged by the inductive 

 action of the transmitted current. It therefore appeared very 

 possible that insulated cables extending to land- or submarine- 

 minc, in which high-tension fuzes were inclosed, might become 

 charged inductively during violent atmospheric electrical dis- 

 turbances to such an extent as to lead to the accidental explosion 

 of mines with which they were connected. In a Report by vrn 

 Ebner on the defence of Venice, Tola, and Lis^a, by submarine 

 mines, in 1866, he refers to the accidental explosion of one of 

 a group of sixteen mines during a heavy thunderstorm, as well as 

 to the explosion of some mines, by the direct charging of the 

 cables, through the firing station having been struck by lijhtning. 

 Two instances of the accidental explosion of tendon fuzes by 

 the direct charging of overhead wires during lightning discharges 

 occurred in 1873 at Woolwich. 



Subsequently an electric cable was laid out at Woolwich along 

 the river bank below low- water mark, and a tendon fuze was 

 attached to one extremity, the other being buried. About 

 eleven months afterwards the fuze was exploded by a charge 

 induced in the conductor during a very heavy thunderstorm. 



In consequence of such difficulties as these experienced in the 

 special application of the high-tension fuzes to submarine pur- 

 poses, the production of comparatively sensitive low-tension 

 fuzes, of much greater uniformity of resistance than these em- 

 ployed in former years, was made the subject of an elaborate 



