232 



SCIENTIFIC NEWS. 



[Sept. 7, 1888. 



with terrific violence, in all directions. Do not suppose I am saying 

 that similar effects cannot be obtained from a gun where wire is not 

 employed. They can be. But my point is, that they can also be 

 obtained by the aid of the insignificant thing which I am holding up 

 at this moment — this piece of steel ribbon, which looks more suit- 

 able for the framework of an umbrella. 



I have already spoken to you, when considering steel as a mere alloy 

 of iron and carbon, as to the value of even a fraction of I per cent, of 

 the latter ; but we know that in actual practice steel almost always 

 contains other ingredients. One of the most prominent of these is 

 manganese. It had for years been used, in quantities varying from 

 a fraction of 1 per cent, up to 2" 5 per cent., with advantage as 

 regards ductility, and as regards its ability to withstand forging. A 

 further increase was found not to augment the advantage : a still 

 further increase was found to diminish it : and here the manufac- 

 turer stopped, and, so far as I know, the pure scientist stopped, on 

 the very reasonable ground that the point of increased benefit 

 appeared to have been well ascertained, and that there could be no 

 advantage in pursuing an investigalion which appeared only to 

 result in decadence. But this is another instance of how the appli- 

 cation of science reacts in the interests of pure science itself. One 

 of our steel manufacturers, Mr. Hadfield, determined to pursue this 

 apparently barren subject, and in doing so discovered this fact — 

 that, while with the addition of manganese in excess of the limit be- 

 fore stated, and up to as much as7per cent., deterioration continued, 

 after this latter percentage was passed improvement again set in. 



Again, the effects of the addition of even the very smallest per- 

 centages of aluminium upon the steel with which it may be alloyed 

 are very striking and very peculiar, giving to the steel alloy thus 

 produced a very much greater hardness, and enabling it to take a 

 much brighter and more silver-like polish. Further, the one- 

 twentieth part of I per cent, of aluminium, when added to molten 

 wrought iron, will reduce the fusing-point of the whole mass some 

 500 degrees, and will render it extremely fluid, and thus enable 

 wrought iron (or what are commercially known as " mitis " — 

 castings of the most intricate character) to be produced. 



No one has worked more assiduously at the question of the effect 

 of the presence of minute quantities, even traces, of alloys with 

 metals than Professor Roberts-Austen, and he appears by his 

 experiments, to be discovering a general law, governing the effect 

 produced by the mixture of particular metals, so that, in future, it is 

 to be hoped, when an alloy is, for the first time, to be attempted, it 

 will be possible to predict with reasonable certainty what the resultwil 

 be, instead of that result remaining to be discovered by experiment. 



I have just, incidentally, mentioned aluminium. May I say that we 

 engineers look forward, with much interest, to all processes tending 

 to bring this metal, or its alloys, within possible commercial use ? 



One more instance of the effect of impurities in metals. The 

 engineer engaged in electrical matters is compelled, in the course of 

 his daily work, frequently to realise the importance of the " next- 

 to-nothing." One striking instance of this is afforded by the influ- 

 ence which an extremely minute percentage of impurity has on the 

 electrical conductivity of copper wire : this conductivity being in 

 some cases reduced by as much as 50 per cent , in consequence of 

 the admixture of that which, under other circumstances, would be 

 looked upon as insignificant. 



Reverting to the question of big guns. According to the present 

 mode of manufacture, after we have rough-bored and turned the 

 "A" tube (and perhaps I ought to have mentioned that by the 

 "A" tube is meant the main piece of the gun, the innermost layer, 

 if I may so call it, that portion which is the full leDgth of the gun, 

 and upon which the remainder of the gun is built up)— after, as I 

 have said, we have rough-bored and turned this " A " tube, we heat 

 it to a temperature lying between certain specified limits, but actually 

 determined by the behaviour of samples previously taken, and then 

 suddenly immerse it perpendicularly into a well some £0 feet deep, 

 full of oil, the oil in this well being kept in a state of change by 

 the running into it, at the bottom, of cold oil conveyed by a pipe 

 proceeding from an elevated oil tank. In this way the steel is oil- 

 hardened, with the result of increasing its ultimate tensile strength, 

 and also with the result of raising its so-called elastic limit. In 

 performing this operation it is almost certain that injurious internal 

 strains will be set up : strains tending to produce self- rupture of the 

 material. Experiments have been carried out in England, by 

 Captain Andrew Noble, and by General Maitland of the Royal Gun 

 Factory, by General Kalakoutsky, in Russia, and also in the United 

 States, to gauge what is the value, as represented by dimensions, of 

 these strains, and we find that they have to be recorded in the most 

 minute fractions of an inch, and yet, if the steel be of too " high " a 

 quality (as it is technically called), or if there has been any want of 

 uniformity in the oil-hardening process, these strains, unless got rid 

 of or ameliorated by annealing, may, as I have said, result in the 

 §elf-rupture of the steel, 



I have spoken of the getting rid of the strains by annealing, a 

 process requiring to be conducted with great care, so as not to pre- 

 judice the effects of the oil-hardening. But take the case of a 

 hardened steel projectile, hardened so that it will penetrate the steel 

 face of compound armour. In that case annealing cannot be 

 resorted to, for the extreme hardness of the projectile must not be 

 in the least impaired. The internal strains in these projectiles are 

 so very grave, that for months after they are made there is no 

 security that they will not spontaneously fracture. I have here the 

 point of an 8-inch projectile, which projectile weighs 210 lbs., this 

 with others was received from the makers as long ago as March of 

 this year, and remained an apparently perfect and sound projectile 

 until about the middle of August — some five months after delivery, 

 and, of course, a somewhat longer time since manufacture— and 

 between August 6th and 8th this piece which I hold in my hand, 

 measuring 3I inches by 3! inches, spontaneously flew off from the 

 rest of the projectile, and has done so upon a surface of separation 

 which, whether having regard to its beautiful regularity, or to the 

 conclusions to be drawn from it as to the nature of the strains exist- 

 ing, is of the very highest scientific interest. Many other cases of 

 self-rupture of similar projectiles have been recorded. 



Another instance of the effect of the " next-to-nothing " is the 

 hardening and tempering or annealing of steel. As we know, the 

 iron and the carbon (leaving other matters out of consideration) 

 are there. The carbon is (even in tool-steel) a very small propor- 

 tion of the whole. The steel may be bent, and will retain the form 

 given to it. You heat it and plunge it in cold water ; you attempt 

 to bend it and it breaks ; but if, after the plunging in cold water, 

 you temper it by carefully reheating it, you may bring it to the con- 

 dition fit either for the cutting-tool for metal, or for the cutting-tool 

 for wood, or for the watch-spring ; and these important variations 

 of condition which are thus obtained depend upon the " next-to- 

 nothing " in the temperature to which it is reheated, and therefore 

 in the nature of the resulting combination of the ingredients of which 

 the steel is composed. 



Some admirable experiments were carried out on this subject by 

 the Institution of Mechanical Engineers, with the assistance of one 

 of our Vice-Presidents, Sir Frederick Abel, and the subject has also 

 been dealt with by an eminent Russian writer. 



There is, to my mind, another and very striking popular instance 

 (if I may use the phrase) of the importance of attention to detail — 

 that is, to the " next-to-nothing." Consider the bicycles and tricy- 

 cles of the present day — machines which afford the means of health- 

 ful exercise to thousands, and which will, probably within a very 

 short time, prove of the very greatest possible use for military 

 purposes. The perfection to which these machines have been brought 

 is almost entirely due to strict attention to detail ; in the selection 

 of the material of which the machines are made ; in the applica- 

 tion of pure science (in its strictest sense) to the form and to the 

 proportioning of the parts, and also in the arrangement of these 

 various parts in relation the one to the other. The result is that the 

 greatest possible strength is afforded with only the least possible 

 weight, and that friction in working has been reduced to a mini- 

 mum. All of us who remember the hobby-horse of former years, 

 and who contrast that machine with the bicycle or tricycle of the 

 present day, realise how thoroughly satisfactory is the result of this 

 attention to detail — this appreciation of the " next-to-nothing." 



Let me give you another illustration of the importance of small 

 things, drawn from gunnery practice. 



At first sight one would be tempted to say that the density of the 

 air on the underside of a shot must, notwithstanding its motion of 

 descent, be so nearly the same as that of the air upon the upper side 

 as to cause the difference to be unworthy of consideration, but 

 we know that the projectiles from rifled guns tend to travel 

 sideways as they pass through the air, and that the direction 

 of their motion, whether to the right or to the left, depends on 

 the "hand" of the rifling. We know also, that the friction 

 against liquid or against gaseous bodies varies with the densities 

 of these bodies, and it is believed that, minute as is the difference 

 in density to which I have referred, it is sufficient to determine 

 the lateral movement of the projectile. This lateral tendency 

 must be allowed for, in these days of long ranges, in the 

 sighting and laying of guns, if we desire accuracy of aim, at those 

 distances at which it is to be expected our naval engagements will 

 have to be commenced, and perhaps concluded. We can no longer 

 afford to treat the subject as Nelson is said to have treated it, in one 

 of his letters to the Secretary of the Admiralty, who had requested 

 that an invention for laying guns more accurately should be tried. 

 Nelson said he would be glad to try the invention, but that, as his 

 mode of fighting consisted in placing his ship close alongside that of 

 his enemy, he did not think the invention, even if it were successful, 

 would be of much use to him. 



While upon the question of guns, I am tempted to remark upon 



