June 2 2, 1876] 



NATURE 



175 



those which are found in greatest numbers in Itajahy 

 {Acrcea Thalia only perhaps equalling or even surpassing 

 them in number), the frequent occurrence of orange- 

 coloured or scarlet flowers in that country is probably less 

 an adaptation to humming-birds than to this fondness of 

 Callidryas. The red Salvia, Canna, the orange-coloured 

 species of Lantana, Epidendron cinnabarimim, &c., are 

 assiduously visited by Callidryas. 



Lippstadt, May 13 Hermann Muller 



LOAN COLLECTION OF SCIENTIFIC 



APPARA TUS 



SECTION— MECHANICS 



PRIME MOVERS'- 



'll/E now come to Newcomen, who I think may fairly be looked 

 * * upon as the father of the steam-engine in its present form. 

 No. 1,942 is a model of his engine, which is further illustrated byia 

 rare engraving (of 1712), the property of Mr. Bennet Woodcroft. 

 Here we have the steam boiler, the cylinder, the piston and 

 rod, the beam working the pumps in the pit, the injection into 

 the cylinder and the self-acting gear, making altogether a power- 

 ful and an aucomatic prime mover. 



That conscientious writer, Belidor, to whom I have already 

 frequently referred, says, that he hears of one of these machines 

 having been set up in the water-woiks on the banks of the 

 Thames at York Buildings. I may say to those who are not 

 aware of it, that those works were situated where the Charing 

 Cross Station now stands. On a Newcomen engine being erected 

 in France at a colliery at Fresnes, near Conde, Belidor paid 

 several visits to it in order that he might understand its construc- 

 tion thoroughly, and be thereby enabled to explain it to his 

 readers. He has done so with a minuteness and faithfulness of 

 detail, in description and in drawings, that would enable one to 

 repeat the engine. This engine had a 30-inch cylinder with a 

 6-feet stroke of the piston and of the pumps. The boiler was 

 9 feet in diameter and 3I feet deep in the body ; it had a dome 

 which was covered with masonry 2 feet 6 inches thick to hold it 

 down against the pressure of the steam. It had a safety valve 

 (the Papin valve) which Belidor calls a " Ventouse," and says 

 that its object was to give air to the boiler when the vapour was 

 too strong. It had double vertical gauge cocks the function of 

 which Belidor explains ; it made fifteen strokes in a minute ; and 

 he says that being once started it required no attention beyond 

 keeping up the fire, that it worked continuously for forty-eight 

 hours, and in the forty- eight hours un watered the mine for the 

 week, whereas previously to the erection of the engine the 

 mine was drained by a horse-power machine, working day and 

 night throughout the whole week and demanding the labour of 

 filty horses and the attendance of twenty men to keep the water 

 down. I should have said that the pumps worked by the steam- 

 engine were 7 inches bore and were placed 24 feet apart verti- 

 cally in the pit which was 276 feet deep, and that each pump 

 delivered into a leaden cistern from which the pump above it 

 drew. 



After having given a most accurate description of the engine, 

 Belidor breaks out into a rhapsody and says (I will give you a 

 free translation) " It must be acknowledged that here we have 

 the most marvellous of all machines, and that there is none other 

 of which the mechanism has so close a relation to that of ani- 

 mals. Heat is the principal of its movements ; in its various 

 tubes a circulation like that of the blood in the veins is set up ; 

 there are valves which open and shut j it feeds itself, and it per- 

 forms all other functions which are necessary to enable it to 

 exist," 



Smeaton employed himself in perfecting and in properly pro- 

 portioning the Newcomen engine, but it was not imtil James 

 Watt that the next gieat step was made ; that step was as we all 

 know the doing away with condensation in the cylinder, the 

 effecting it in a separate vessel and the exclusion of the atmos- 

 phere from the cylinder. These alterations made a most important 

 improvement in the efficiency of the engine in relation to the 

 fuel consumed ; but they were so simple that I doubt not if ex- 

 aminers into the merits of patents had existed in those days Mr. 



• Address delivered by K. J. Bramwell, CE., F.R.S., one of the vice- 

 presicents of the SectioD, May 25. Continued from p. i6i. 



Watt would have had his application for a patent rejected as 

 being "frivolous." We have here from case No. 1,928, a model 

 made by Watt which appears to be that of the separate condenser 

 and air-pump ; we have also 8b which is a wooden model made 

 by Watt of a single acting inverted engine, having the top side 

 of the cylinder always open to the condenser, and a pair of valves 

 by which the bottom side of the piston can be put into alternate 

 connection with the boiler and with the condenser, the contents of 

 which are withdrawn by the air-pump. 3B from the same case 

 is a model of a direct acting inverted pumping engine, made in 

 accordance with the diagram 8b. i b is a model of Watt's single 

 acting beam pumping engine, while 2B is a model of Watt's 

 double acting beam rotary engine. lOB from the same case is 

 Watt's model of a surface condenser. To Watt we owe, con- 

 densation in a separate vessel, exclusion of the air from ".the 

 cylinder, making the engine double acting, employment of the 

 steam jacket, and employment of the steam expansively, the 

 patallel motion, the governor, and in fact all which made New- 

 comen's sirgle acing reciprocating pumping engine into that 

 anachine of universal utility that the steam-engine now is, and 

 not only so, but Watt invented the steam-engine indicator which 

 enables us to ascertain that which is taking place within the 

 cylinder and to see whether or not the steam is being economi- 

 cally employed. I have on the table before me a vevy excellent 

 model of German manufacture, No. 2,137, illustrating an inverted 

 direct acting pumping engine in its complete form, and I have 

 also a model of French manufacture, the cylinder and other 

 working parts of which are in glass ; this shows a form of Watt 

 rotary beam condensing engine at one time in common use. 



I do not say, however, that Watt was the first to make the 

 suggestion of attaining rotary motion from the power of steam. 

 Leaving out of consideration Hero's toy, Papin, as I have re- 

 marked, hoped to get rotary movement second-hand by working 

 a water wheel with the water that had been ra sed by his steam- 

 engine ; moreover, as early as 1737, Jonathan Hulls proposed to 

 obtain rotary motion from a Newcomen engine and to employ 

 that motion in turning a paddle-wheel, to propel a tug-boat 

 which should tow ships out of harbour, or even against an ad- 

 verse wind. I have before me one of the prints of his pamphlet 

 and in order that you may better appreciate his iiivention I have 

 put an enlarged diagram upon the wall, and I think I may take 

 this as the starting-point for saying a few words about the steam- 

 engine as a prime mover in steam vessels. 



We have in the collection, No. 2,150, Symington's engine tried 

 upon the Lake at Dalswinton in 178S. Here a pair of single 

 acting vertical cylinders give, by the up and down motion of their 

 pistons, reciprocating movement to an overhead wheel ; this wheel 

 gives a similar motion to an endless chain which chain is led 

 away so as to pass round two pairs of ratchet wheels loose upon 

 two paddle shalts. By the use of a pair of ratchets the recipro- 

 cations of the chain are converted into rotary motion in one 

 direction only, and that the driving direction of the two paddle 

 wheels placed one behind the other. Symington's arrangement 

 for obtaining the rotary motion always in one direction of his 

 two paddle-wheels is very similar to that proposed by Jonathan 

 Hulls for his single stem-wheel. Want of time forbids me to 

 do more than just to allude to the names of Homblower and 

 Wolff in connection with double cylinder engines, engines where- 

 in the expansion of steam is commenced in one cylinder and con- 

 tinued in another and a larger one. 



I wish to say a few words which will bring before you the 

 changes that have been made within a very few years in the con- 

 struction of the marine engines. I may observe that when I was 

 an apprentice the ordinary working pressure of steam, except in 

 the double cylinder engine, was only 3 lbs. above atinosphere, 

 and that there was in a marine boiler more pressure on its bottom 

 when the steam was down, due t j the mere head of water in the 

 boiler, than there was pressure in the top when the steam was up, 

 due to the force of the steam ; whereas now condensing marine 

 engines work commonly at 70 lbs., and there is a boat under 

 trial where the steam is, 1 believe, as high as 400 lbs. 



To those who are curious on the sabject, I would recommend 

 a perusal of two blue books, one being the evidence taken before 

 a Parliamentary Commission in 181 7, and the other before a 

 Pariiamentary Committee in 1839 ; they will find there the 

 weight of evidence to be that the only use of high pressure steam 

 is to dispense with condensing water, and that as a steamboat 

 must always have plenty of condensing water in its neighbour- 

 hood, no engineer knowing his business, would suggest high 

 pressure for a marine enjjine. 



I have before me a model of a pair of engines which, although 



