Aug. 19, 1875] 



NATURE 



3^5 



shells of ordinary construction, elaborated by Prof. Abel 

 nearly three years ago, by which the breaking up of cast 

 iron shells into a large number of fragments and their 

 dispersion with considerable violence is accomplished by 

 filling the shell with water instead of with an explosive 

 agent. 



In a memoir communicated by Mr, Abel to the Royal 

 Society in 1873,* it was pointed out that detonation was 

 transmitted from a mass of dry compressed gun-cotton 

 to distinct masses of the material saturated with water 

 and separated from each other and from the detonat- 

 ing (or " initiative ") charge by small spaces filled with 

 water, the whole being enclosed in a case of stout 

 wrought iron ; and Mr. Abel stated that the sudden- 

 ness and completeness with which detonation was trans- 

 mitted through small water-spaces had suggested to him 

 the possibility of applying water as a vehicle for the 

 breaking up of cast iron shells into numerous and com- 

 paratively uniform fragments, through the agency of force 

 suddenly developed in the perfectly closed shell, com- 

 pletely filled with water, by the detonation of a small 

 quantity of gun-cotton or other similarly violent explosive 

 substance, immersed in the water, Mr. Abel considered 

 that if such a result were obtained, a shell or hollow pro- 

 jectile of the most simple construction could be made 

 readily to fulfil the functions of the comparatively com- 

 plicated shrapnel and segment shells which have been 

 specially designed to furnish a large number of dangerous 

 missiles when burst during their flight. 



A few experiments with ordinary cast iron shells, 

 spherical and cylindro - conoidal, afforded conclusive 

 demonstration of the power possessed by water, in virtue 

 of its slight compressibility, to bring to bear uniformly in 

 all directions upon the walls of the shell, the force deve- 

 loped by an explosion which is made to occur suddenly 

 in the completely confined water-space, and showed, 

 moreover, that the disruptive effect was proportionate 

 not merely to the amount of explosive agent used, 

 but also to the suddenness of the concussion imparted 

 to the completely confined water by the explosion. In 

 illustration of the disruptive effect of water, the fol- 

 lowing results may be quoted from a number given by 

 Mr. Abel in his memoir. A i6-pounder (cylindro-co- 

 noidal) shell, filled with 16 ounces of gunpowder, was 

 broken by the explosion of this charge into 29 frag- 

 ments. The detonation of a quarter of an ounce of gun- 

 cotton confined in a shell of precisely the same construc- 

 tion and weight, the chamber being filled up with water 

 and tightly closed, burst the shell into 121 fragments, 

 which were violently dispersed. A corresponding charge 

 of gun-cotton, confined in a third similar shell, the 

 chamber being filled with air, did not burst the shell when 

 detonated ; the resulting gases found vent through a minute 

 perforation in the plug or screw-stopper of the shell. One 

 ounce of gun-cotton confined in a similar shell, filled up 

 with water, broke it up into 300 fragments, but in addition 

 there were 2 lb. i oz, of the shell almost pulverised by 

 the force of the explosion brought to bear upon the metal 

 through the agency of the confined water. 



The manner in which Mr. Abel has applied this system 

 of bursting shells is very simple. The fuse which is used in 

 field-artillery service for bursting shrapnel-shells or the 

 common shell (when the latter is filled with gunpowder and 

 used as amine or an [incendiary projectile), has fitted to 

 it a small metal cylinder closed at one end, into which is 

 tightly packed from a quarter to one-half ounce of dry 

 comp«ssed gun-cotton. The open end of the cylinder is 

 closed with a screw plug containing a small chamber 

 filled with fulminate of mercury, the upper side of which 

 is in close contact with the fuse when the cylinder has 

 been attached to the latter. To employ common shells 

 as water-shells it is now only necessary to fill them com- 



' Contributions to the History of Explosive Agents, Second Memoir, by 

 F. A. Abel, F.R.S.— Phil. Trans. 1874, p. 373. 



pletely with water, and then to insert and screw down 

 firmly the fuse with its little detonating cylinder attached, 

 when the detonating charge is fired by the action of the 

 fuse, the shell is instantaneously burst into a large num- 

 ber of fragments by the concussion transmitted by the 

 water, 



Mr. Abel's prediction that this plan of bursting shells 

 would be found most effective, is amply borne out by the 

 magnificent practice made by the field-guns at Oke- 

 hampton. Of the two batteries of Royal Artillery which 

 have carried on the experiments during the past week, 

 one has done more mischief with the " water-shells " than 

 with the delicately constructed shrapnel, with the nature 

 of which the gunners are intimately acquainted ; while 

 with the other battery of heavier field-guns the practice 

 made was but little inferior. A little better acquaintance 

 on the part of artillerymen with the new system of using 

 shells will, it is anticipated, still further increase the 

 deadly effect of these terrible weapons. Moreover, the 

 water-shell has hitherto only been used in conjunction 

 with a percussion fuse, while it is with the time-fuse that 

 the shrapnel-shell is found the most effective. With the 

 percussion-fuse the two shells are about on an equality, 

 while the water-shell has the advantage of greater sim- 

 plicity. 



NOTES FROM THE ''CHALLENGER'' 



THE following extracts from a letter dated Yeddo, 

 June 9, 1875, addressed to me by Prof. Wyville 

 Thomson, will, I think, interest the readers of Nature : — 



" In a note lately published in the proceedings of the 

 Royal Society on the nature of our soundings in the 

 Southern Sea, I stated that up to that time we had never 

 seen any trace of the pseudopodia of Globigerina. I 

 have now to tell a different tale, for we have seen them 

 very many times, and their condition and the entire 

 appearance and behaviour of the sarcode are, in a high 

 degree, characteristic and peculiar. When the living 

 Globigerina is examined under very favourable circum- 

 stances ; that is to say, when it can at once be transferred 

 from the tow-net and placed under a tolerably high 

 power in fresh, still sea-water, the sarcodic contents of 

 the chambers may be seen to exude gradually through 

 the pores of the shell and spread out until they form a 

 gelatinous fringe or border round the shell, filling up the 

 spaces among the roots of the spines and rising up a 

 little way along their length. This external coating of 

 sarcode is rendered very visible by the oil-globules, which 

 are oval and of considerable size, and filled with intensely 

 coloured secondary globules ; they are drawn along by 

 the sarcode, and may be observed, with a little care, fol- 

 lowing its spreading or contracting movements. At the 

 same time, an infinitely delicate sheath of sarcode con- 

 taining minute transparent granules, but no oil-globules, 

 rises on each of the spines to its extremity, and may be 

 seen creeping up one side and down the other of the 

 spine, with the peculiar flowing movement with which we 

 are so familiar in the pseudopodia of Gromia, and of 

 the Radiolarians. If the cell in which the Globigerina is 

 floating receive a sudden shock, or if a drop of some irri- 

 tating liquid be added to the water, the whole mass of 

 protoplasm retreats into the shell with great rapidity, 

 drawing the oil-globules along with it, and the outline of 

 the surface of the shell and of the hair-like spines is left 

 as sharp as before the exodus of the sarcode. We are 

 getting sketches carefully prepared of the details of this 

 process, and either Mr. Murray or I will shortly describe 

 it more in full. , . . 



" Our soundings in the Atlantic certainly gave us the 

 impression that the siliceous bodies, including the spicules 

 of Sponges, the spicules and tests of Radiolarians, and the 

 Pustules of Diatoms which occur in appreciable propor- 

 tions in Globigerina ooze diminish in number, and that 



