444 



NATURE 



{Sept. 6, 1888 



employed for that which I may call standing engineering work 

 — i.e. buildings, bridges, aqueducts, and so on — while timber, 

 cast iron, and wrought iron were for many years the only avail- 

 able materials for the framing and principal parts of moving 

 machines and engines, with the occasional use of lead for the 

 pipes and of copper for pipes and for boilers. 



As regards the cast iron, little was known of the science 

 involved (or that ought to be involved) in its manufacture. It was 

 judged of by results. It was judged of largely by the eye. It was 

 "white," it was "mottled," it was "gray." It was known to 

 be " fit for refining," fit for " strong castings," or fit for castings 

 in which great fluidity in the molten metal was judged to be of 

 more importance than strength in the finished casting. With 

 respect to wrought iron, it was judged of by its results also. It 

 was judged of by the place of its manufacture — but when the 

 works of the district were unknown, the iron, on being tested, 

 was classed as "good fibrous," although some of the very best 

 was "steel-like," or "bad," "hot-short," or "cold-short." A 

 particular district would produce one kind of iron, another 

 district another kind of iron. The ore, the flux, and the fuel 

 were all known to have influence, but to what extent was but 

 little realized ; and if there came in a new ore, or a new flux, it 

 might well be that for months the turn-out of the works into 

 which these novelties had been introduced would be prejudiced. 

 Steel again— that luxury of the days of my youth — was judged 

 by the eye. The wrought bars, made into "blister" steel by 

 "cementation," were broken, examined, and grouped accord- 

 ingly. Steel was known, no doubt, to be a compound of iron 

 and carbon, but the importance of exactness in the percentage 

 was but little understood, nor was it at all understood how the 

 presence of comparatively small quantities of foreign matter 

 might necessitate the variation of the proportions of carbon. 

 The consequence was that anomalous results every now and then 

 arose to confound the person who had used the steel, and, falsify- 

 ing the proverb "true as steel," steel became an object of 

 distrust. Is it too much to say that Bessemer's great invention 

 of steel made by the " converter," and that Siemens's invention 

 of the open-hearth process, reacted on pure science, and set 

 scientific men to investigate the laws which regulate the union of 

 metals and of metalloids? and that the labours of these scientific 

 men have improved the manufacture, so that steel is now 

 thoroughly and entirely trusted ? By its aid engineering works 

 are accomplished which, without that aid, would have been 

 simply impossible. The Forth Bridge, the big gun, the 

 compound armour of the ironclad with its steel face, the pro- 

 jectile to pierce that steel face — all equally depend upon the 

 " truth " of steel as much as does the barely visible hair-spring 

 of the chronometer which enables the longitude of the ship 

 in which it is carried to be ascertained. Now, what makes 

 the difference between trustworthy and untrustworthy steel 

 for each particular purpose ? Something which, until our better 

 sense comes to our aid, we are inclined to look upon as ridicu- 

 lously insignificant — a "next-to-nothing." Setting extraneous 

 ingredients aside, and considering only the union of iron and 

 carbon, the question whether there shall be added or deducted 

 one-tenth of 1 per cent, (pardon my clumsy way of using the 

 decimal system) of carbon is a matter of great importance in the 

 resulting quality of the steel. This is a striking practical 

 instance of how apparently insignificant things may be of the 

 highest importance. The variation of this ' fraction of a per- 

 centage may render your boiler steel untrustworthy, may make 

 the difference between safety in a gun and danger in a gun, and 

 may render your armour-piercing projectile unable to pierce even 

 the thinnest wrought-iron armour. 



While thus brought incidentally to the subject of guns, let me 

 derive from it another instance of the value of small things. I 

 have in my hand a piece of steel ribbon. It is probable that 

 only those who are near to me can see it. Its dimensions are 

 one-fourth by one-six'eenth of an English inch, equal to an 

 area of one sixty-fourth of a square inch. This mode of stating 

 the dimensions I use for the information of the ladies. To 

 make it intelligible to my scientific friends, I must tell them 

 that it is approximately "00637 of a metre by approximately 

 •00159 of a metre, and that its sectional area is "0000101283 (also 

 approximately) of a square metre. This insignificant (and 

 speaking in reference to the greater number of my audience), 

 practically invisible piece of material — that I can bend with my 

 hand, and even tie into knots — is, nevertheless, not to be 

 despised. By it one reinforces the massive and important- 

 lookiDg A-tube of a 9 "2-inch gun, so that from that tube can be 



projected with safety a projectile weighing 380 pounds at jjj 

 velocity, when leaving the muzzle, of between one-third and 

 one-half of a mile in a second, and competent to traverse nearly 

 \i\ miles before it touches the ground. It may be said, " What 

 is the use of being able to fire a projectile to a distance which 

 commonly is invisible (from some obstacle or another) to the 

 person directing the gun ? " I will suggest to you a use. Imagine 

 a gun of this kind placed by some enemy who, unfortunately, 

 had invaded us, and had reached Richmond. He has the range- 

 table for his gun ; he, of course, is provided with our Ordnance 

 maps, and he lays and elevates the gun at Richmond, with the 

 object of striking, say, the Royal Exchange. Suppose he does 

 not succeed in his exact aim. The projectile goes 100 yards to 

 one side or to the other ; or it falls 250 yards short, or passes 

 250 yards over ; and it would be "bad shooting " indeed, in these- 

 days, if nearly every projectile which was fired did not fall some- 

 where within an area such as this. In this suggested parallelo- 

 gram of 100,000 square yards, or some 20 acres, there is some 

 rather valuable property ; and the transactions which are carried 

 on are not unimportant. It seems to me that business would 

 not be conducted with that calmness and coolness which are 

 necessary for success, if, say, every five minutes, a 380-pound shell 

 fell within this area, vomiting fire, and scattering its walls in 

 in hundreds of pieces, with terrific violence, in all directions. 

 Do not suppose I am saying that similar effects cannot be ob- 

 tained 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 suitable 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 1 

 per cent, of the latter ; but we know that in actual practice steel 

 almost always contains other ingredients. One of the most pro- 

 minent 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 advantages 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 manufacturer 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 investigation 

 which appeared only to result in decadence. But this is another 

 instance of how the application of science reacts in the interests 

 of pure science itself. Oneof our steel manufacturers, Mr. Hadfield r 

 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 before stated, and up to as 

 much as 7 per cent., deterioration continued, after this latter 

 percentage was passed improvement again set in. 



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

 percentages 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 1 per cent, of aluminium, when added 

 to molten wrought iron, will reduce the fusing-point of the whole 

 mass some 500°, 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 Prof. 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, ill 

 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 result will 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 pro- 

 cesses 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 woik, frequently to realize the importance of the 

 "next to-n'othing." One striking instance of this is afforded by 

 the influence which an extremely minute percentage of impurity 

 has on the electrical conductivity of copper wire ; this con- 



