1843.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



210 



OSCILLATING MARINE ENGINE. 



Patented by Messrs. Mather, Dixon & Grantham, of Liverpool. 



( With an Engraving, Plate IX.) 



We have given a drawing of a pair of marine engines, on a plan 

 lately patented by Messrs. Mather, Dixon and Grantham, of Liver- 

 pool, for an improved method of driving screw propellers; and we 

 shall endeavour in a future number to add another arrangement show- 

 ing nearly the same form of engine, but suited to vessels having a 

 deeper hold than is required for the engines we now present to our 

 readers. 



Fig. 1, shows the half-side elevation of the engines, with one air 

 pump and condenser. 



Fig. 2, shows the other half elevation, with the engine turned 

 round, representing the side opposite to the air pumps. 



Fig. 3, is a ground plan of the whole arrangement, the cylinder on 

 one side being removed. 



It will be readily understood that these engines have oscillating cy- 

 linders, placed at right angles and opposite to each other, the piston 

 rods being each attached to one crank. In the annexed drawings the 

 cylinders are represented as working downwards, the object of this 

 evidently being to allow the propelled shaft to be placed near the 

 bottom of the vessel. 



The engines are constructed with a foundation plate to which are 

 attached the side frames that carry the cylinders; the pedestal of the 

 main shaft is attached to the bed plate having the condensers cast on 

 it; a small counter shaft is employed to work abeam which gives 

 motion to two air pumps; one gudgeon of the beam rests on one of 

 the side frames of the cylinders, and the other is supported by a small 

 standard rising up from the condensers. It is intended to have short 

 stroked engiues, and to work them faster than is usual in sea-going 

 steam vessels, but not faster than is now usual on the Thames; by this 

 means we shall presently endeavour to show that high velocities may 

 be obtained without employing multiplying gearing. 



It is unnecessary to enter into a more detailed description, as in all 

 minor points nothing new is contemplated, the proportions and mode 

 of working, which is found favourable with engines driving paddle 

 wheels, will be equally applicable to these engines, excepting that 

 the makers prefer having two air pumps with a short stroke instead 

 of one. 



As the advantages which may be expected from the employment of 

 the screw propeller are of very great importance, and as the plans, 

 which we are now considering, seem likely to remove many of the 

 obstacles which have hitherto impeded its progress, we shall not he- 

 sitate to present to our readers some additional particulars of the 

 plans by which Messrs. Mather, Dixon and Grantham propose to 

 carry their project into effect, as well as an account of what they 

 have already effected in a small vessel built by them, which has for 

 some months been at work on the Mersey. It is from these results 

 that they have founded their calculations of what may be effected in 

 vessels of large dimensions. 



We gave a brief notice of this vessel in our last number, and are 

 promised the particulars of some accurate experiments which it is 

 intended shall be made with her. We need only now say that she 

 has more than realised the expectations of the builders, and from 

 their report it appears to be the most satisfactory trial yet made on 

 the screw as a means of propelling vessels. The propeller employed 

 was patented by Mr. Woodcroft, in 1830. We hope in another 

 number to be able to give a description of this also. 



The mode of constructing the screw, supporting the shaft, the ap- 

 paratus for regulating the endward pressure of the shaft, and other 

 details, will come under our notice as we proceed. All, in our opi- 

 nion, being matters of deep interest and importance to those concerned 

 in steam navigation, when on the eve, as we firmly believe, of a great 

 improvement to this truly national question. 



We will now only add a few remarks on the principal features of 



No. 70.— Vo l. VI.— July, 1843. 



the improvements here proposed, to show that it will not be necessary 

 to introduce any system of working that has not under other circum- 

 stances been advanfageously applied before, although not in the same 

 combination. From the results given by the " Liverpool screw," it is 

 stated that the advantage over paddle wheels, is fully 25 per cent, 

 when under the most favourable circumstances for the latter, but that 

 in towing and in rough weather, the gain by the screw when applied, 

 as now proposed, is found to be nearly 50 per cent. It is therefore 

 presumed that for general purposes two-thirds the engine power only 

 will be requisite for the screw, that is necessary in paddle-wheel ves- 

 sels, to give a certain speed. It is also found that if the pitch of the 

 screw is made 2£ times its diameter, a very reduced amount of slip 

 varying from 5 to 10 per cent, will take place, and that it is probable 

 for light vessels and high velocities the pitch may be made three 

 times the diameter of the screw. It is also clearly established that no 

 disadvantage results from placing the screw one-third out of water. 

 The steering is not perceptibly injured by it, and the loss from slip 

 not increased, and it is expected that instead of its being an objection, 

 it will be fouud more convenient for ordinary practice than when the 

 screw is entirely immersed. This point we shall discuss when we 

 describe the construction of the screw itself. 



THE AERIAL TRANSIT MACHINE. 



Analysis of the projected Aerial Transit Machine, and of the principles 



invoiced in its construction and employment. 



( Concluded from page 191. J 



Throvghout the preceding portions of this inquiry, which have 

 appeared in succession in our last two numbers, our purpose having 

 been to illustrate the operation of the parts, rather than to determine 

 the efficiency of the whole, we have taken a view of the case simpli- 

 fied in a manner which, if it were the true one would, however appa- 

 rently exaggerated the obligations, represent the object as neverthe- 

 less within the reach of art to accomplish, even with the means, be 

 they ever so moderate, which the projector might have at his disposal. 

 The unlimited declension of the force by which the machine, regarded 

 as a mathematical plane (incapable of generating any resistance but 

 that which belongs to it as such) would be opposed in its horizontal 

 progress, in a degree proportioned to the angle of its inclination, 

 would, however remote, still indicate a point at which this obstacle 

 would have been so far reduced that any power, however feeble, 

 would be adequate to the accomplishment of the rate necessary to 

 produce the desired result. In theory it is perfectly true that a 

 mathematical plane of any proportion of weight and dimensions hypo- 

 thetically assignable, could, by the exercise of any amount of propul- 

 sive energy (sufficient to overcome the friction of the parts) be made 

 capable of sustaining itself in the air ; a rate of motion equivalent to 

 the production of a vertical resistance adequate to its support being 

 as surely attainable at some angle of inclination, as any effect is surely 

 consequent upon its cause where there is no force in operation to pre- 

 vent it. But the difficulty of the matter lies here — the machine is not 

 a mathematical plane, nor by any mode of construction could ever be 

 rendered so ; and the interference of its solid parts, in the resistance 

 they experience in the air, however restricted by the contrivances of 

 art, introduces a new ingredient of opposition, which, not following 

 the same rule of reduction, but on the contrary, increasing with the 

 process by which the former is nullified or avoided, puts a limit to the 

 extent to which that process with its attending advantages may be 

 carried, and thus removes the case out of the category of results 

 necessarily attainable by the exercise of art. Before, therefore, any- 

 thing can be positively concluded with respect to the success of any 

 particular scheme of flight upon the principle of the plan before us, 

 we must be satisfied that a power is at command competent to the pro- 

 duction of a velocity equivalent to the support of the machine, 

 restricted by this new element of resistance — »he interference of its 

 solid parts, 



3D 



