1847. 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



289 



clack made of leather, witli a plate of iron secured to the flap ; and 

 as a substitute for the hinge valve, formerly described, we liave a 

 |iiece of wood made to slide through the top, and in two grooves, 

 one at each side of the pipe. The machine being immersed beneath 

 the surface of the river, and a communication made between the suc- 

 tion pipe and the interior of the dam, it only remains to raise the 

 slide S, and permit a current to be established inside of the main 

 pipe or box; then by pushing the slide down, a vacuum would 

 instantly be formed, which, as before explained, would elevate the 

 water from the interior of the dam, to be expelled into the river when 

 the slide was again raised. 



I have erected a machine of this form ; and as it can be constructed 

 and put in operation in a few hours, and as it is both effective and 

 costs but little, I recommend it to parties who have hydraulic works 

 in progress, where the situation will admit of its being employed. 



In conclusion, this machine is obviously applicable to the raising of 

 water, or producing a vacuum, in every situation where we can com- 

 mand a fall or running stream ; and experiment having proved it to 

 be superior to the undershot water-wheel, for these purposes, whilst 

 with this great power it combines simplicity, durability, and cheap- 

 ness, in the highest degree, I am humbly of opinion that it is likely 

 to be extensively employed, in which case, the foregoing description 

 will not have been written in vain. 



RAILWAY-CARRIAGE BREAKS. 



At the last quarterly meeting of the Institute of Mechanical Engineers, 

 held at Birmingham, Mr. J. G. M'Connell in the chair, the following com- 

 munications were read : — 



Mr. G. Stephenson, President of the Institute, " On a new Self-acting 

 Break,"* a beautiful model of which accompanied the paper. 



"The various accidents on railways arising from concussions and collisions 

 (and especially the late accident at Wolverton) have induced me to draw my 

 attention to the construction of a self-acting break, which I have for several 

 years had in view, a plan and model of which I have had made, and now 

 lay before the Society, with my description of its action and effects. When 

 a railway train is moving at the rate of from 40 to 60 miles an hour, the mo- 

 mentum is so great that it cannot be stopped In any reasonable distance by 

 the breaks at present in use ; or if an axle-tree breaks, or any accident happen 

 to the engine so as to prevent its progressing, the sudden shake causes the 

 carriages to overturn each other, and those next the engine are almost certain 

 to be crushed. In an accident of this kind, neither engine-driver, stoker, or 

 guard can be prepared, and before there is time for any of them to put on the 

 break at present in use, so as to be in the least degree effective, the collision 

 or concussion has taken place. When the engine-driver shuts off the steam 

 or applies his break on the tender, the self-acting break is immediately 

 brongiit to bear upon every wheel attached to every carriage in the train so 

 powerfully, if necessary, as to bring every wheel into the condition of a 

 sledge. I think the train will be brought to a stand by this break in one 

 tenth of the space in which it can be by the breaks at present used. My 

 plan is as follows : — I attach a couple of spiral springs to the levers of the 

 break of every carriage, and also connect them with the buffers, and if the 

 carriage requires gentle breaking (which will always be the case when a train 

 approaches a station), the engine-driver, by shutting off a portion of the 

 steam, or applying the break gently, will have complete command over the 

 train, without any of those violent uneasy motions, which are very frequent 

 and excessively disagreehle to passengers ; and as the guard is frequently 

 compelled to apply his break so powerfully as to make the wheels slide on 

 the rail, and cause a considerable amount of wear and tear on the tyre of the 

 wheel, by which it becomes flat-sided, and makes the carriages uneasy, and 

 creates ajumping motion on the rail. Suppose a train of carriages moving 

 at the rate of from 30 to 40 miles an hour, and a signal is held out for the 

 engine-driver to stop; the moment he shuts off the steam, the whole of the 

 breaks are brought into instant application of sledging the wheels, which will 

 be more effectual than fifty men applying the common breaks, as the mischief 

 is frequently done before the guard is apprised of the approach of danger. 

 It is frequently necessary for the trains to be backed into a siding. When 

 this is required, the train will first have to be stopped, and in one minute the 

 whole of the breaks can be disengaged from the buffers, as is shown in the 

 model, and *vhen the train proceeds they are again dropped into gear. The 

 plan altogether appears so simple that any ordmary mind can easily under- 

 stand the whole of it ; and I think the cost of putting the breaks on each 

 carriage would not exceed more than from 51. to 10/. Any effectual plan 

 for increasing the sat'ety of railway travelling is, in my mind, of such vital 

 importance, that I prefer laying my scheme open to the world, to taking out 

 a patent for it ; and it will be a source of the greatest pleasure to me to 



* A railway brealc, answeriug a similar purpose as the one described by Mr. Stephen- 

 son, has b«eii ppltiited by Mr. Bunnet, and described in the •' Journal" for ld42, page 72. 

 —Ed. C. E. & A. Journal. 



know that it has been the means of saving even one human life from de- 

 struction, or that it has prevented one serious concussion." — In consequence 

 of Mr. Stephenson's absence, the invention was not discussed, it being agreed 

 that a special meeting should be called to consider the subject. 



The consideration of Mr. Buckle's experiments on fan blasts, now exciting 

 considerable interest, was tiien resumed. The chief object of Mr. Buckle 

 was to show that the present fan blasts were imperfect in construction and 

 expensive in operation. lie proposed, as the result of experiments extending 

 over a period of nine years, to have a series of fans, revolving in such a way 

 as that the blast of air thrown from one would be communicated to each. 

 He also showed the advantages of having a large inlet-pipe. By these means 

 he estimated that not only would the blast be stronger with less horse power, 

 but it would also be uniform ; thus improving the quality of the iron, as well 

 as producing it at a cheaper rate. 



DREDGE'S SUSPENSION BRIDGE. 



Sir — I beg, in reference to an extract you made from a Calcutta paper, in 

 the last number of your Journal, to observe that I published no statement in 

 the Mecha lies' Magazine that I have not documents and drawings by me to 

 substantia; ;. 



Bath, Aug. 23, 1847. James Dredge. 



REVIE'WS. 



Tables /or the Calculation of Earthnorla. By F. Bashforth, M.A. 



In our last notice of Mr. Bashforth's tables, we explained to our 

 readers the method of determining the volume of earthwork when the 

 height of the slopes on either side was the same, and the calculation 

 involved only integral numbers in feet and chains; we now propose 

 to show how the tables can be applied to determine the amount of 

 earth both in ordinary and side-long cuttings, when the heights contain 

 decimal portions of feet. Suppose, as before, the slopes of the side- 

 long cutting to be produced until they meet in some straight line be- 

 low the formation level; then if the vertical sections of such a cutting 

 be similar triangles, we can apply the tables to determine the 

 quantity of earth excavated ; all we have to do then is to determine 

 the area of these triangular sections a chain apart, take the square 

 root of the areas, and substitute them for the a and 6 of the tables. 

 For the method of using the scale of proportional parts we shall quote 

 the following example, given by Mr. Bashforth himself: — 

 "Suppose a = 37-68 i= 12-53. 



By the general table {37-12} = 1595 

 Place 37 on (A) \ f^^ ( -6 we get 42 



opposite 12 on (B) J ' \ -08 „ 



Place 12 on (A) \ J. / -5 we get 



opposite 37 on (B) / ""^ \ -02 „ 



Therefore {37-68, 12-53} = 1669- nearly." 



The mode of construction of the scale is so minutely explained by 

 the author, that any illustrations of our own would be quite super- 

 fluous. In conclusion, we cannot but express a hope that this will not 

 be the last time we shall have the pleasure of recording Mr. Bash- 

 forth's useful labours. It is not saying too much to assert that no 

 other member of the profession possesses an equal amount of scientific 

 knowledge with Mr. Bashforth; and we trust that gentleman will not 

 allow the talent committed to his care to be idle. There is plenty of 

 room, and plenty of occupation for men of science amongst engineers ; 

 and while we are willing to admit the paramount importance of a 

 practical acquaintance with details, we must firmly declare that un- 

 less the engineer combines with that knowledge of facts a knowledge 

 of principles, the lives of the public will be jeopardied whenever 

 they are intrusted to the stability of his structures. 



The Double Gauge.— Observations by Mr. R. Stephenson, on Mr. 



Brunel's report on the Double Gauge. 



The public were greatly indebted to the scientific labours of Mr. 

 Robert Stephenson for opposing the fallacious reasonings of the advo- 

 cates of the atmospheric railway system, in the height of its popu- 

 larity — he has now, in a work recently issued under the above title, in 

 a masterly manner laid the axe at the root of the double gauge system, 

 recently promulgated and proposed to be adopted on the Oxford and 



39 



