176 



NATURE 



{June 22, 1876 



they were made not so very long ago (for I saw them put into 

 the ship), have nevertheless an historical interest. This model 

 shows Maudslay's engines of the Great Western, the first steamer 

 built for the purpose of crossing the Atlantic. I think I am 

 right in saying that 7 lbs. steam was the pressure employed in 

 that vessel, and in order to extract the brine from the boiler it 

 was necessary to use pumps as the pressure of the steam was not 

 sufficient to expel the brine and to deliver it against the pressure 

 of the sea. 



Time does not permit of my touching upon the various im- 

 provements in boilers, condensers, expansive arrangements, and 

 other matters which have gradually been introduced into our best 

 engines for land and for ocean purposes. I have hung upon the 

 wall a rough diagram showing a pair of oscillating^ engines as 

 applied to driving a paddle steamer, and another showing a pair 

 of inverted compound cylinder engines to drive a screw propeller ; 

 a model of such a pair of engines with surface condensers and all 

 modern appliances (being Messrs. Rennie's engines for the P. and 

 O. Company's S.S. Pera, by which I have had the pleasure of 

 travelling) is now before me. 



I will conclude this part of the subject by saying that to the 

 combination of science and sound practice is due the fact of the 

 consumption of coal having been reduced from 5 lbs. per gross 

 indicated horse-power per hour to an average of 2\ lbs. and, in 

 exceptional instances, to as small a quantity as i4 lbs. per horse 

 per hour. 



Let us now devote a little of the time that is left to the con- 

 sideration of the locomotive on the common road as well as on 

 the railway. I have before me No. 2,145, ^ model of the actual 

 engine of Cugnot, in the Conservatoire des Arts et Metiers, which, 

 in 1769, journeyed — slowly, it is true, but did journey and did 

 carry pas-sengers — along the roads in Paris. 



It is a most ingenious machine ; it has three wheels, and the 

 motive power is applied to the front, the castor, or steering 

 wheel, so that engine and boiler turn with the wheel precisely 

 as, within the last few years, Mr. Perkins has caused the engine 

 and boiler to turn with the steering-wheel of his three- wheeled 

 common road locomotive. The steam causes the pistons in a 

 pair of inverted single acting cylinders to reciprocate, and their 

 rods, -by means of ratchet wheels, give rotary* motion to the 

 castor wheel, and thus propel 'the carriage. I think there is no 

 doubt but that we must look ii'pon 'this engine of Cuqnot as the 

 lather of steam locomotion, as we must regard Symington's 

 engine as the parent of marine propulsion. I have before me 

 No. 1,926, Trevethick's engine of 1802 ; I have also before me 

 a Blenkinsop rail, one that has been in actual use for many 

 years, provided, as you will see, with teeth, into which a cogged 

 riange on the side of the driving-wheel is geared to insure that 

 tractive force should be obtained. This plan has been revived, 

 within the last few years, to enable the steam locomotive to 

 climb the Righi. A sketch of the Righi engine and rail is on 

 the wall. It will be seen that the teeth instead of projecting 

 from the sidefof the rail, are ranged between two parallel bars 

 like the rungs of a ladder. 



On the ground-floor of the exhibition we have the veritable 

 " Pufhng Billy," an engine which began work in 1813, and got 

 along without the aid of cogs by mere adhesion upon plain 

 rails ; it is a rude-looking machine, but it laboured up till the 

 date of the last Exhibition, doing its work for forty-nine years 

 on the railway belonging to the Wylams Colliery, and, as tra- 

 dition says, interesting George Stephenson, who, as a boy, saw 

 it in daily operation. 



On the ground-floor, also, we have 1,954, the "Rocket," with 

 which seventeen years after the starting of "Puffing Billy" 

 George Stephenson carried off the prize in the Manchester and 

 Liverpool Railway competition. The leading particulars of this 

 engine are as follows : — A pair of 74 inch cyhnders l' 5" stroke, 

 placed at a slight inclination driving 4' 6" wheels, the boiler, 

 multi-tubular, having twenty-four three and a half-inch tubes, 

 while the fire is urged by the waste blast. Before alluding 

 to this I ought to have mentioned that in one of the Blue Books 

 to which I have called your attention — that which gives the evi- 

 dence before the Commission in the year 1817 — there is a state- 

 ment by a witness that in those parts there are machines called 

 locomotives, &c. 



Once more I am compelled to say that time will not admit of 

 my entering into any detail in respect of the modern locomotive, 

 except to remark that by the aid of excellent boilers, of high- 

 pressure steam (140 lbs. to the inch) of considerable, although 

 rather imperfect expansion effected by the link motion, there is 

 provided for the use of our railways a machine which in the 



" passenger " form is competent to travel with ease and safety 

 sixty miles an hour, and in the * ' goods " form is competent to 

 draw a load of 800 to i,cx)0 tons, and to attain these results with 

 a very commendable economy in fuel. I have put on the wall 

 two diagrams of locomotives of the convenient form for local 

 traffic that we call tank engines, and I have before me No. 

 i,957<z, a most beautifully made sectional working model of a 

 Russian six-wheeled " goods " engine. 



Within the last twenty years another description of steam- 

 engine has acquired a prominent and important place among our 

 prime movers ; I allude to the portable engine, or to the portable 

 engine in its more complete form of a self-propelling or traction 

 engine. The general construction of these machines borders 

 closely upon that of the locomotive. Very great attention has 

 been paid to all their details, and the Royal Agricultural Society 

 of England, by their excellent arrangements for periodical trials, 

 have stimulated engineers to devote their best energies to the 

 subject. No. 1,942 is a model of one of Aveling and Porter's 

 common road traction engines, capable also of acting as a source 

 of power for driving farm-yard machinery or for effecting steam- 

 ploughing. Upon the wall I have placed rough diagrams of 

 another kind of traction engine — a kind wherein india-rubber 

 tires are used ; this is manufactured by Messrs. Ransome, Sim?, 

 and Head, and I have also placed there diagrams of the ordinary 

 portable engine and of another most useiul kind of portable 

 engine, viz., the steam fire-engine. I have there likewise a 

 sketch of Hancock's common road steam coach, which for so 

 many months regularly plied for hire from the Bank to Padding- 

 ton in opposition to the ordinary horse omnibus. Hancock's 

 carriage was a vehicle which, in my judgment, has never since 

 been surpassed, and I am sorry to say never to my knowledge 

 equalled as regards the various points which should be attended 

 to in making a steam carriage to circulate safely among horse- 

 traffic. 



There is another way in which steam may be employed as a 

 prime mover. We saw that water in the form of the " Trombe 

 d'eau" CLuld be caused to induce a current in air and thereby to 

 blow a forge fire, and that a rapid stream induces a current in 

 other water, and thus drains marshy lands. Similarly steam can 

 be caused to induce a current in water and thtreby impel the 

 water so as to raise it to a height or to force it as feed-water into 

 a boiler against a heavy pressure. When used for a mere 

 pumping apparatus, such a mode of employing steam is very 

 wasteful, because the steam is condensed by the water in large 

 quantities and the water is needlessly heated at the expense of 

 the steam ; but when used in feeding a boiler into which, thus, 

 the whole of the heat is taken, this objection does not apply. 

 By means of that most elegant and scientific apparatus, the 

 Giffard injector, it is possible, by a jet of steam, to economically 

 induce a current in surrounding water, powerful enough to take 

 the condensed steam itself and the water into the boiler from 

 which the steam had previously issued. No. 1,976, which I 

 have before me, is a sectional model of a Giffard injector. 



I believe it was I who first gave a popular explanation of the 

 principle of action of the Gifilard injector, and although a scien- 

 tific congress is probably not the place for a popular explanation, 

 I will venture to repeat it. The principle may be summed up 

 in one word, "concentration." The steam that issues from an 

 orifice of an area of I, when condensed, has a sectional area 

 (according to the original pressure of the steam) of only ^l^^^th 

 Of T^T^h or ^^Tjth as the case may be, thus the velocity remaining 

 the same and the weight the same, the energy of the steam 

 issuing from an area of i, is concentrated 200, 400, or 800 times 

 upon the area due to the smaller transverse section of the liquid 

 stream. 



This concentration of energy is far more than sufficient to 

 enable the fluid stream to re-enter the boiler from which the 

 vaporous stream started, and so much more than sufficient, that 

 it may be diluted by taking with it a certain quantity of water, 

 which was employed in the condensation of the steam, and is 

 required for the feeding of the boiler. 



With a view to obtaining economy- in fuel many attempts have 

 been made to employ some other agent than steam as the means 

 of developing the power latent in fuel, but it is imperative that 

 I should dismiss these with a mere enumeration. A very inter- 

 esting engine of this kind (because, excluding Hero's toy and 

 smoke jacks, it is so far as I know the first proposition for ob- 

 taining rotatory motion by the aid of heat), was the fire wheel of 

 M. Amonton, of which an account is to be found in the first 

 volume of the "French Academy of Sciences," for the year 

 1699. On referring to that volume I do not see that it is stated 



