AbeVs Fuses and Wheatstone's Exploder. 167 



the now comparatively worthless low-lying lands bor- 

 dering on -the Yarra Yarra River. 



In preparing this paper and accompanying diagrams, I 

 have been and am much indebted to the kind courtesy of 

 Commander Cox, and the Government astronomer, Mr. 

 Ellery, for the use of the tide and meteorological registers 

 necessary for the compilation of the facts put forward, and 

 take this opportunity of tendering my thanks for the same. 



Melbourne, 10th October, 1864. 



Art. XL. — Abel's Fuses and Wheatstone's Exploder. By 

 R L. J. Ellery, Esq., F.RA.S. 



[Read 18th July, 1864.] 



Mr. Ellery (the Government Astronomer) exhibited some 

 of Abel's patent fuses, with an instrument called " Wheat- 

 stone's Exploder," together forming a most convenient and 

 powerful means of firing gunpowder by electricity. 



Mr. Ellery described the exploder, which is in fact a port- 

 able magneto-electric apparatus, as consisting of a set of 

 compound permanent magnets, arranged around a cube, 

 armed with electro-magnetic coils, in front of the poles of 

 which, soft iron armatures could be made to revolve rapidly 

 by turning a handle, giving rise to a pretty powerful 

 induced electric current in the fuse covering wire of the 

 coil ; which, by means of suitable connections, could be con- 

 ducted to considerable distances through properly insulated 

 wire. The whole apparatus was conveniently enclosed in a 

 mahogany case, 8 or 9 inches square, and weighed about SO 

 pounds. 



The fuses exhibited were of two kinds. The ones for 

 firing guns were very similar in appearance to the ordinary 

 friction tube, with the exception that to one end was attached 

 a small knob of beech wood, perforated with two holes, 

 which were copper-lined and served to hold the connecting 

 wires when ready for firing. The other fuses were adapted 

 to blasting purposes, and consisted of a small wooden car- 

 tridge filled with powder, to which was attached a pair of 

 insulated wires about two feet long, with which the connect- 

 ing wires had to be joined when used. The principal point 

 of interest in these fuses was the use of a peculiar composi- 

 tion, very susceptible of ignition by the slightest electric 

 spark. This composition was placed in contact with the two 



