28+ 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



LSbptembeb, 



imporlant mailer is its being generally looked upon as a thankless sort of 

 job, Ilie engine-man always considering it an extra duty, for which he 

 claims extra allowance, and the master consitleriug that he pays him sufti- 

 ciently to include that work with his other duties. The results consequent 

 upon inattention to boiler cleaning, require no comment here ; every prac- 

 tised engineer being well ac(]uainted with them, knows that if actual 

 explosion does not happen, tlie tear and wear upon those parts most 

 exposed to the fire mu.-t be greatly increased, and so keep up a heavy ex- 

 pense in repairs, independent of the immense quantity of extra fuel that is 

 required to keep up the steam. 



•' I trust these remarks will suffice to draw the attention of the Institution 

 to this very important subject, and that the proprietors of steam-power 

 may be convinced that the small extra outlay required to make the boilers 

 perfectly safe, will be more than repaid by the ecouoiuy in working." 



ON THE FALLACIES OF THE ROTARY ENGINE. 



Before entering on this consideration of the subject, the President in- 

 vited Mr. Onions, who is not a member of the Institution, to describe a 

 disc engine, of which he is the inventor, and to stale wherein it dillered 

 from other rotary engines. He claimed for his engine a superiority over 

 the crank principle in power and saving of fuel ; the chief peculiarity, 

 however, being an improvement in the mode of packing, so (as was 

 alleged) as to make its parts perfectly tight. Mr. Onions asserted, that 

 the loss of power in the use of the crank was estimated by some eminent 

 men at -j-jlhs. This, he stated, was saved by his engine. There was no 

 friction, and yet by this moCe of packing, all leakage was obviated. — 

 After a few remarks cuudeninalory of the principle, the President pro- 

 ceeded to read his paper on this sniijeit. As the explanations were ac- 

 companied by references to diagrams, we adopt so much of the paper as 

 will give an idea of Mr. Stephenson's argument. He remarked that, as 

 all levers gave out their power at right angles to their fulcrums, it would 

 be been that a right-itngle line from the connecting-rod to the centre of the 

 beam would be the true measure of the length of tlie beam when the crank 

 was at half-stroke— therefore, the i^th of half the length of the beam 

 would be gained by the pislonend of the beam. The crank being 3 feet 

 loug, the up and down stroke of ihe piston would he 12 feet ; the crank- 

 pin woulil, of course, have passed through a space of nearly 19 feet. 

 Now, a weight hanging upon a drum nearly 4 feet diameter, would 

 balance the same weiglit on the piston-end of tlie beam ; each would 

 move at the same velocity, and pass through the same space in the same 

 time. It would he observed, that from C to U on the diagram was a little 

 more than one-third longer than from G to D ; it would, therefore, be seen 

 that the weight at the piston end of the beam had a little more than one- 

 third advantage ovef ilie weight of the drum. And it would also be seen 

 that from C to E was half-way frmu lialf-slroke to the bottom centre ; at 

 this portion of the stroke the leverage of the crank would he nearly 2 feel. 

 The increased power that existed in the crunk from half-stroke to this point 

 would gradually be lost from E to H ; it was, llierefure, clearly pro\ed 

 that no power was lost by the craiik-iiiniion. as the weiLhts resolved them- 

 fcelves into a simple lever. There wuuld be a little loss of power when the 

 engine was turning the ci'nires, which is conipeosateil for at the connecting- 

 rod end of the beam by the segment of the right-angle line. Now a rotary 

 engine could only give out its power on the arm like any other lever; and 

 if the piston parsed through a space of 19 feet, it would just baUnce a 

 weight equal to the same power passing through the same space. The 

 President, in contiuualrn, said that no man could improve the lever ; it 

 was useless to talk at that lime of day of the loss of power by the crank : 

 tliere was no such loss. He asked, what had been the performance of filr. 

 Onions' engine at Derby, where it was tried? 



Mr. Onions said that in those experiments the saving was equivalent to 

 20 percent. Would the President believe the fact if he saw it? 



The Pri;sident, with good-humoured warmth, exclaimed, " No, I 

 wouldn't, Sir. I would believe I was mad first, or that there was magic 

 iu the experiment." 



Mr. IMiLLER, of Blackwall, remarked that there was no loss of power 

 by the crank; and he niiglit also add that nobody, he believed, objected 

 to the principle of the rotary-engine, except so far as regarded the dilli- 

 cultj, or rather the impossibility, of packing it perfectly tight. No doubt 

 the rotary-engine had its advantages, such as its application to the screw 

 in marine engineering, and wherever small space and considerable power 

 was necessary ; but the rock upon which inventors split, was the packing. 

 He would as soon thiuk of iuventiug perpetual niuiiou as uf overcoming 

 that diHiculty. 



BRITISH ASSOCIATION. 



Notes fiom the Proceedings of the Meeting held at ivausea, August, 1848. 



Applicatio.-* of Heated Gases from Furnaci-s. — At the Ystalafera 

 Iron-works near Swansea, under the management of Mr. Uudd, a valuable 

 application has been made of the heated gases that are usually pei mitted to 

 escape from blast furnaces. The heated gases are in the first instance con- 

 du':led through horizontal passages at the top into a stove, where they heat 

 the compressed air in its passage to the furnace to form the hot blast. 1 he 

 air which is conveyed to the stove in a convolution of pipes is heated in this 

 Uiaiinei to about 700° or ajC". The heated gases after having done duty in 



the stove, are conducted under the boilers of the engine employed for com- 

 pressing the air, and experience has proved that the boilers can he heated in 

 tills manner more clitctively than by fuel, with the additional advantage 

 that there is no corrosion of the iron. Only one of ihe boilers at the 

 Ystalafera works is as yet fitted up in this manner, but the experiment has 

 answered so well, that all the boilers will shortly be heated in a similar 

 manner ; and thus the power for compressing the air and the means of heat- 

 ing it w-iil he procured by using the mere waste heat of the furnaces. The 

 " hot-blast" will by this means cost literally nothing, and it is estimated 

 that if the plan be carried out through all the iron-works in England and 

 Wales, there will be an annual saving of f 1,200,000, without taking into 

 account the saving arising from the diminished wear of the iron in the 

 boilers and the heating tubes. Even this saving might be increased, for at 

 present the heated gases are permitted to escape unconsumed ; and by a 

 judicious admission of air to supply the required oxygen for combustion, the 

 heated gases might be advantageously burned. In this manner some of the 

 furnaces in Belgium were economically managed several years ago, the heat 

 of the consumed gases being employed in various processes. 



A Drt Condenser. — Mr. Joseph Price made a communication in the 

 Mechanical Section, of a plan that he has lately adopted in the construction 

 of marine engines, and which he then made public for the first time. The 

 engines constructed by Mr. Price combine the effects of high pressure and of 

 condensing engines. The steam is worked at a pressure of aliout 20 lb. to 

 the square inch, and it issues from the cylinder, after having done its work 

 there, into a dry condenser. The condenser consists of a chamber containing 

 several pipes, through which the water passes as the vessel is propelled for- 

 ward, and by this means the pipes are kept cool. The steam emitted from 

 the cylinder meets, as Mr. Pi ice expressed it, with a " cold reception" in the 

 condensing chamber, and the water of the condensed steam collects at the 

 bottom, whence it is forced again into the boiler by a small force-pump. In 

 this manner the boiler is constantly supplied with fresh water, even at sea, 

 and there is consequently no incrustation. This arrangement of the condenser 

 would admit of the use of spirits of wine instead of water, if the waste by 

 leakage could be avoided. 



Low-Pressurb Atmospheric Railway. — A large model of a low- 

 pressure atmospheric railway was exhibited in the Mechanical Section, by its 

 inventor, M. Struvu. In this plan the original mode of atmospheric pro- 

 pulsion is adopted, the carriages and passengers being all inclosed within the 

 atmospheric pipe. It is proposed, howe\er, to construct the atmospheric culvert 

 of brick-work, and it is to be illuminated by windows; so that the passengers, 

 though inclosed, will not be excluded from daylight. A shield is fixed to 

 the carriages, against which the pressure of the atmosphere is to act ; and as 

 the requisite pressure need only he very low, there is no necessity to be 

 particular about the shield being air-tight at the edges — indeed, it is intended 

 that it should move without any friction against the sides. With an area 

 large enough to admit the railway carriages, it is calculated that a pressure 

 of six-tenths of an inch would be sufficient for ordinary speeds, and it is 

 proposed to obtain that amount of exhaustion by large pumps formed some- 

 thing like gasometers, which work up and down in water, and expel the air 

 from the large pipe. The estimate for constructing a railway of this kiud is 

 £7,00J per mile. 



The Iron Produce op Pennsylvania. — It was stated by Professor 

 Rogers, of Pennsylvania, in the Geological Section, that the annual quantity 

 of iron produced in that state exceeds the whole annual produce of South 

 Wales ; the estimated quantity being 700,000 tons. 



The Colouring Property of Maddcr. — Dr. Edward Schnnck pre- 

 sented to the Chen.ical Section his third report on the colouring property of 

 madder. The extractive matter of madder-root contains seven difi'erent sub- 

 stances, only one of which, however — the alizarine — is of value for its colour ; 

 all the others, indeed, tend to impair the colour yielded by alizarine ; and 

 the chief use in adding lime to madder in dyeing is, that it combines with 

 the other substances, and renders them harmless. Potass, or other alkalies, 

 would have a similar effect ; but as lime is cheaper, there would be no 

 advantage gained in substituting alkalies. It was suggested that a practical 

 application might be made of the analysis, by extracting the alizarine in a 

 separate stale, freed from the injurious adjuncts, in which condition it was 

 hoped a better and more durable pijiment might he obtained, especially in 

 the madder lakes. The experiments have, however, been so recently made, 

 that no practical results can as yet be expected. 



The Effect of Light in Photography. — M. Claudet and Mr. Hunt 

 brought before the Chemical Section some curious facts relative to the effect 

 of light on photographic pictures. In taking a Daguerreotype picture, it is 

 well known that the plate, after being exposed for the proper time in the 

 camera, presents no image, and that it is not till after exposure to the 

 vapour of mercury that the picture is developed. M. Claudet has ascertained 

 that the red, yellow, and orange rays have nearly the same effect as mercury 

 vapour ; and that on a plate exposed to those rays, after having been in the 

 camera, the picture is developed nearly as powerfully as where mercury is 

 used. Not only have the red, orange, and yellow rays the property of bring- 

 ing out the invisible picture, hut they act also as accelleratois, in the same 

 way as bromine ; thus, if a prepared plate be exposed in the camera too 

 short a time to produce a distinct picture by mercury vapour alone, the » 

 effect may be increased, and the picture be rendered distinct by exposure to 

 yellow, orange, or red light. Red light alone, however, seems to produce no 

 etfect on a sensitive Daguerreotype plate, and tome curious images of the 



