August 14, 1890] 



NA TURE 



.^81 



Now, by the formula 



7 (P- 305), 



4- .-.-2. 



where 



so that 



'0 



= (A + 0^2^- 



A =/o 



- if 



ti=t{r,-r)lr-p, " , ' "^ -, ; 



and the expression for the winding tension, 9, finally reduces to 

 the form — 



L . M . N 



where 



A = 



e = A + 



_ A^o-ir^- 



r + r. 



r^\r.^ - V) 



-A, 



N 



t{r^ 



o) - A^ 



('-2 + ^o) + A''0 



after considerable algebraical reduction. 



(55) A great simplification is introduced if we put r^ = r^ 

 equivalent to supposing that the jacket C fits loosely over the 

 coil B, so that the firing stresses do not extend into the jacket 

 c, which, therefore, now contributes nothing to the strength of 

 the gun ; and now A = o, L = - /;-„, M = ^/-j - (if + A)^o> 

 N = /rg + (/ + /o)''o; and we thus obtain the formula (51) of 

 Longridge's " Treatise," or formula (50) of Moch's article. 



With the numbers of Fig. 10, we find flj = 34, while obviously 

 we always have Q.^ = (p.^, as the winding tension of the last layer 

 of wire is the same as the tension in repose. 



Having plotted out by points the curve fli^g ^°^ t^e winding 

 tension 0, a curve of the fourth degree, it will be found practi- 

 cally correct enough to replace it by the most approximate 

 straight line ; and now in winding the coil, the difference of the 

 tension weights destined for two consecutive layers of wire re- 

 mains constant. 



(56) We have now finished the theory of the wire gun, so far 

 as the circumferential strength is concerned ; and for its experi- 

 mental verification, an interesting article in Note No. 38, on the 

 Construction of Ordnance, "On Winding and Dismantling an 

 Experimental Wire-wound Gun Cylinder," by Lieutenant W. 

 Crozier (Washington, June 1886), may be consulted ; and ac- 

 cording to recent reports a lo-inch gun has been recently con- 

 structed in America by Captain Crozier, on designs based upon 

 his experimental results. 



The theory of the longitudinal stresses in the wire gun has 

 not been touched upon, because it is still a point of dispute as to 

 whether the tube alone should provide the longitudinal strength, 

 or whether it should be partly borne by the outside jacket, the 

 wire coil being obviously unable, except in Canet's double 

 coning system, of giving any assistance in this direction. 



Mr. Longridge's principle of strengthening a tube with wire, 

 wound with appropriately varying tension, will be found useful 

 in peace and in war : he can claim credit that a gun strengthened 

 on this principle, the 9 ■2-inch wire gun, was chosen from its 

 great strength to test the extreme range of modern artillery in 

 1888, with what were called the "Jubilee rounds " ; when, with 

 an elevation of about 40°, a range of 21,000 yards, or 12 miles, 

 was attained, the projectile weighing 380 pounds, and the 

 muzzle velocity being about 2360 f.s. 



The dimensions in the diagrams have been purposely taken in 

 round numbers, so as not to represent invidiously any particular 

 gun ; in some cases, inappropriate stresses have made their ap- 

 pearance ; and now it is the art of the gun-designer to modify 

 slightly the dimensions of the parts of his first rough sketch, so 

 as to attain to more uniformity of strength and a better theoretical 

 result. 



There is no claim to originality in the theory that has been 

 given above, and we fear that due credit has not always been 

 properly assigned to the right investigator ; but _the attempt has 



NO. 1085, VOL. 42] 



been made to present the essential points of the theory in as 

 simple a form as possible, with a minimum recourse to algebrai- 

 cal formulas. The subject has been written about so much of 

 late years that the reader is apt to be confused with the variety 

 of notation and treatment ; and it is hoped that the graphical 

 method presented here will enable the theorist to present his 

 results to the practical gun-maker in a more intelligible and 

 convincing form, A. G. Greenhill, 



Jl 



ON PUTREFACTIVE ORGANISMS} 



HE author said his difficulty was to decide in which way to 

 treat his subject. He might summarize the investigations 

 of twenty years, and endeavour to show the original motives 

 which led to their being undertaken, and then contrast this with 

 the new meaning which has been derived from the investigations 

 founded on recent methods and instruments ; or, secondly, he 

 might show the results of a series of continuous observations on 

 certain saprophytic organisms placed under increasingly adverse 

 environments, so as to endeavour to discover their behaviour in 

 regard to the great Darwinian law. He inclined to this last as 

 the view of his work that might have the broadest interest to a 

 Society like that he was addressing ; but the value of the 

 improvements in recent lenses led him to give the priority to the 

 results so obtained. In the case of larger animals, it was well 

 known that a change of environment produced changes in the 

 organism ; but that these changes were hard to follow up, owing 

 to the few generations that come under the notice of the student 

 or observer. But in the case of micro-organisms the generations 

 succeed each other so rapidly that it is easy to follow the changes 

 produced by environment. He could show the effect on certain 

 micro-organisms of a gradual change of temperature, and how 

 in from seven to eight years an organism arose which lived and 

 multiplied at a temperature of 157° F., whose ancestors had 

 lived at a temperature of 65° F., and would have died if exposed 

 to temperatures above 100°. He said there was nothing harder 

 than to carry an audience to a just appreciation of the lower 

 forms of life, but nevertheless he hoped to point out some of the 

 practical results due to the improvements in'modern microscopes. 

 If they took a glass of drinking-water and put in it some shreds 

 of fish, or any other organic substance, it soon became turbid 

 and charged with the minutest organisms. To illustrate the 

 number of these organisms. Dr. Dallinger said that visible to 

 the human eye in the heavens there were in all probability with 

 our most powerful modern telescopes 100,000,000 stars ; and if 

 they supposed that each of these, like our sun, was attended by 

 eight primary bodies and twenty secondary planets, there would 

 be two thousand eight hundred millions of bodies in space 

 accessible to human research. The same number of these 

 minute organisms to which he had referred would lie in a space 

 equal to one ten-thousandth of a cubic inch. Any such a 

 molecule of even dead matter must arrest the attention of the 

 human mind ; but when we remembered that these were complex 

 vital forms, they had a significance of a high order, and their 

 inconceivably rapid multiplication would make the mind pause 

 and think. A decomposing mass of matter was a mass of beings 

 endowed with life, and producing definite products. The life of 

 the organism was not even an incidental product, the organisms^ 

 were there for a purpose. They break up the decomposing 

 organic matter into its elements, and so make it ready again for 

 the purposes of life. Dr. Dallinger went on to describe 

 some of the organisms which he has observed and examined. 

 He said, that if they took some putrescent fluid from different 

 putrefactive material, and mixed them, then put a very minute 

 quantity of sterilized fluid on the microscope slide, and put into 

 this the point of a needle which had been inserted into the 

 mixture of putrefaction, and examined it with a sufficiently 

 powerful microscope, the field of view in the microscope became, 

 as it were, charged with life in an instant. There were many 

 kinds of organisms, and they had many movements. There 

 were rod-shaped organisms, spiral forms, a perfect oval form with 

 two flagella, or whips. Another would be like the calyx of a 

 papilionaceous flower, and have four flagella. Another would 

 have a delicate egg-shape, and another be shaped like a double 

 convex lens, and move with a beautiful wave motion. The fluid 

 speck seen under the microscope was densely peopled. What 

 were these organisms, and what their functions amid the denizens 



' Abstract of an Address delivered before the'^Bristol Naturalists'i Society, 

 by the Rev. W, H. Dallinger, F.R.S. 



