1842. J 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



177 



MARINE ENGINES BY MESSRS. MILLER, RAVENHILL & Co. 



Patented by Joseph Miller. 



(With an Engraving, Plate VI.) 



The object of this arrangement of machinery is to economise room, 

 and this object is certainly very completely attained-, a power of 

 upwards of 300 horses occupying only S feet in the length of the ves- 

 sel and 18 feet in the breadth. There are, it is true, certain counter- 

 vailing disadvantages — for example, the connecting rods, as well as 

 the eccentric rods, are short, occasioning not merely an increased 

 friction in the working of those parts, but disturbing the movement 

 proper to the slide valves, and there is the want of that equilibrium 

 of weight so nicely preserved by the side lever principle. These 

 defects attach either wholly or partially to all engines of the direct 

 action description ; so that the gain in space and lightness is not a 

 gain without any deduction. In these engines they are mitigated as 

 much as possible by placing the cranks at such an angle as to preserve 

 the balance as nearly as may be, myX by such a configuration of the 

 upper and under slide-vaive faces as will neutralize the effect of the 

 distorted movement, consequent upon the shortness of the connecting 

 and eccentric rods. 



The nature of Messrs. Miller & Co.'s arrangement is rendered so 

 obvious by the accompanying drawing, that any detailed explanation 

 of it would be a mere waste of words. The connecting rods are 

 attached to the tops of the piston rods, the latter being maintained 

 in the perpendicular position by means of guides G G, Fig. 3, in which 

 cross heads work, one of which is shown at H, Fig. 1. There are two 

 air-pumps, and the vessel in which condensation is accomplished, and 

 which fills the whole space between the cylinders, is divided by a 

 diaphragm so as to make it, in fact, two condensers, each with its own 

 air-pump immersed in it, so that no sole plate is requisite ; great 

 strength is attained with a moderate weight of material, and a large 

 power is compressible (so to speak) into a very narrow compass. The 

 air-pumps are of brass, and the buckets are wrought by the cranks 

 C C on the intermediate shaft, and the tops of the air-pump rods are 

 kept in the upright position by the guides g g. M M are the man- 

 hole doors of the condensers : BB are strong flanges or brackets, 

 through which the bolts pass for securing the engines to the vessel's 

 bottom. 



We understand Messrs. Miller and Ravenhill are now constructing 

 a pair of these engines for the British government, the cylinders of 

 which are 155 inches in diameter, and the length of the stroke 5 feet= 

 308 H.P. ; also a pair for the French government, the cylinders of 

 which are G8 inches in diameter, and the length of the stroke 5 ft. G in. 

 = 340 H.P. One pair of these engines is nearly completed. 



The general character of Messrs. Miller & Co.'s machinery may, we 

 conceive, be summed up in a few words. With a destitution of em- 

 bellishment which, in some cases, we are disposed to regard as the 

 result of too severe a philosophy, there is an excellence of materials 

 and workmanship, and a superiority of proportion and arrangement, 

 united with an efficiency and an economy of performance which we 

 do not believe have ever been surpassed. In the minutest details of 

 the work, as well as in its leading features, there are evidences of a 

 profound acquaintance with the subject, both in its practical and phi- 

 losophical relations. Where such anxiety exists to render the quality 

 of work unexceptionable, and is united with so much ability and so 

 much experience, it is impossible that its quality should be any other 

 than of the very first description ; and it is therefore far from sur- 

 prizing that Messrs. Miller's machinery should be esteemed so highly. 

 The best test of excellence which all can understand is Time ; for 

 that machinery must be admitted to be the best which continues to 

 do the greatest quantity of work at the least expense. But the ad- 

 judication of this high authority is only to be obtained in the lapse of 

 years — it is with difficulty to be obtained at all — and even then it is 

 likely to be the resultant of a variety of circumstances of which the 

 quality of the machinery is only one. Nevertheless, any information 

 57 — V):. . v.— June, 1842. 



we may be able to gather respecting the actual performance of the 

 machinery of any maker must, with all its liabilities to error, be ad- 

 mitted to be a valuable aid towards enabling us to arrive at a right 

 conclusion respecting the probable qualities of any machinery of a 

 similar kind he may propose to furnish. 



RIVER THAMES EMBANKMENT. 



Taile of Distances on the Thames from Fulham Bridge to Blackwall, also 

 the present width and the proposed contraction of the riser as recommended 

 lij Mr. James Walker in his report to the City Corporation. 



2 C 



