3^6 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[AtTGUST, 



countor pressure arising from the formation of an eddy in the interior ; 

 but this counter pressure is however much less than might be sup- 

 posed. I have demonstrated that when a fluid forms an eddy in the 

 interior of a cylinder, the effects of the centrifugal force show them- 

 selves differently according to the different inclinations of the projec- 

 tions or orifices made on the circumference. 



" In No. 1 Ibe orifices are disposed in the direction in which the cen- 

 trifugal force can least influence the expenditure of wafer. Thus the 

 coefficient of theoretical expenditure due to the work, during the ex- 

 periments on the turbine, which I constructed at Bourges, has been 

 found very little different from that which agrees with the openings 

 of ordinary sluices disposed so as to avoid contraction on three of the 

 sides. The wheel which turned in work, with about half the velocity 

 due to the fall, and the coefficient was 0-70 to 0-79." 



Explanation of the engravings of Passot's turbine, a, b, c, fig- 5, 

 plan of the wheel. A, B, C, fixed base of cast iron. M, N, cover act- 

 ing as a sluice to regulate the expenditure of water, p, q, block of 

 wood carrying the step of the arbour or shaft. E, V, male and female 

 screw serving to regulate the cover by means of the rod T, t, passing 

 through the hollow shaft. L, I, lever to raise the whole motive system 

 by means of the pivot. 



M. Poncelet adopting an arrangement the reverse of that of M. 

 Fourneyron, has proposed a system of turbines of the nature of the 

 horizontal wheels used in the centre and south of France. The water 

 enters by a spout placed on the outside, stretches the vanes, and is 

 discharged by two openings made towards the centre. M. Cardelhac 

 has constructed at Toulouse turbines on this plan, and Messrs. Mellet 

 and Sarrus, of Lodeve,have exhibited one with the same arrangement. 

 The principal part of their turbines consists in a case of particular 

 form, provided with three openings, of which one is for the water to 

 enter, and the two others to allow it to escape after its action on the 

 wheel. In consequence of the spiral form of this casing, the water 

 arrives on the wheel placed in the interior without any shock, and 

 with a velocity due to half the height of the fall. Each of these veins 

 or streams of water acts at the same distance from the axis, as if it 

 were isolated and independent of the other ; its velocity is transformed 

 into pressure by insensible degrees, and without any loss of power. 

 Messrs. Mellet and Sarrus have already put up several of these tur- 

 bines in the South of France with good results. They come cheap, 

 one for an ordinary grist mill costs 40/., one of 12 or 20 horse power, 

 well finished, and of good material, 120/. 



There was at the exposition another hydraulic machine, which the 

 maker, M. de Lamolere/ calls a piston wheel. This machine receives 

 water like a breast wheel. The water brought by means of a plung- 

 ing fan, falls into a bucket, where it stretches a wooden valve, fitted 

 with leather. It passes through this valve, which is followed by a 

 second also. These successive valves turn horizontal shafts, which 

 then give movement to the factory. 



Steam Engines. 



It is noticed that the specimens of steam engines exhibited were 

 more remarkable for variations of form Ihau for novelty of principle. 

 We shall proceed to describe them in their natural order, considering 

 first the furnaces. 



Heating Apparatus. 



M. Arnoux exhibited a furnace for burning the poor coals of the 

 north of France, using a jet of steam of four atmospheres forced 

 through a hole about an Jth of an inch in diameter into a passage about 

 two or three inches in diameter, so as to increase the draft in the 

 engine chimney. In the steamers on the Upper Seine M. Cochot has 

 greatly increased the draft of the boiler, and consequently the produc- 

 tion of steam in a given time, by means of jets in the chimnies. 



M. Wissoc, C. E., exhibited a hollow bar grating, having, more- 

 over, a double bottom so disposed as to send into the interior of the 

 fireplace all the heat which otherwise would be lost in the ash-pit. 

 Messrs. Galy-Cazalat, Martres, and Montaigut, also exhibited eco- 

 nomic gratings, which have been a good deal employed. 



M. Sorel exhibited, under the name of slide grate, a contrivance 

 adapted to the fireplaces of boilers, in order to cleanse them instanta- 

 neously. This is a kind of iron harrow, which with straight teeth 

 cleanses the grates underneath. To obtain forward, backward, and 

 side movements the apparatus is suspended by means of a lever, and 

 can be moved in any direction. The Minister of Marine has directed 

 this to be tried in the navy. 



Boilers and Safety Valves. 

 M. Durenne exhibited a highly finished locomotive boiler. 

 A number of safety valves were exhibited to prevent explosions in 



steam engines. They were generally floating ones, to indicate the 

 quantity of water in the boiler. 



M. Bourdon exhibited a water level indicator, of various forms, with 

 an alarm whistle, one of them is shown in the annexed engraving ; it 

 consists of a small column mounted on the top of the boiler with a flat 

 circular box of cast iron. In the interior is a lever, to the extremity 

 of which is hooked a wire suspending a float, the other end of this 

 lever is adjusted on a steel spindle, with an index fixed on it exter- 

 nally corresponding with the lever, pointing to a graduated arc to in- 

 dicate the level of the water within the boiler ; on the top of the 

 column is an alarum whistle to notify when the water has become too 

 low for safety. Three indicators of this kind are applied on the great 

 boilers of the steam engine at Marly. 



Messrs. Destigny and Langlois exhibited a clock work governor, 

 which also gives the alarm in case of danger by ringing a bell. M. 

 Bernard, of Rouen, had a similar one. 



A great number of the usual knick knacks in the way of safety 

 valves were exhibited. 



Self-regulaiing Expansion Slide Valve. 

 M. Farcot has improved the self-regulating expansion slide valve 

 of Mr. H. H. Edwards (given in our Journal, Vol. VI. p. 49j. The 

 principal improvement consists chiefly in using two slides instead 

 of one. This is a description of the plan. The principal means of 

 distribution is the slide valve A, (fig. G, plate XIII.) on which are 

 placed two slide plates dd, pierced with several openings correspond- 

 ing with other openings made in the back of the valve and communi- 

 cating with the chambers b b. When the openings of the slide plates 

 are put opposite to the openings in the back of the valve the steam 

 enters the steam passages b b, and can reach the passages o o, which 

 open into the piston when they are uncovered by the alternate move- 

 ment of the slide valve A. The slide plates dd, are carried along with 

 the valve, so long as they are not stopped, either by the guide rods//, 

 which touch the extremity of the steam chamber 6, or by the brackets 

 i i, when they meet the tappet c. The length of the guide rods //, is 

 calculated so as to place the openings in the slide plates opposite those 

 in the valve, each time that the latter, in its alternate movement 

 arrives at the end of its course. The tappet c, fig. 7, is a double cam 



