1843.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



367 



DIRECT ACTION ENGINES. 

 (With an Engraving, Plate XIII.) 

 Description of a pair of George Forrester & Co.'s improved Double 

 Cylinder Marine Engines, constructed by than, and Jilted on board the 

 "Helen Mac Gregor," Hull and Hamburgh steamer. Engines in- 

 vented by Benjamin Hick, of the above Jinn, Liverpool. 



These engines are of the form usually denominated "Direct Action 

 Engines," but differing considerably in arrangement, and possessing 

 many advantages over the various forms of direct action engines 

 hitherto made. 



The collective power of the engines is 220 H.P. The accom- 

 panying engraving represents a perspective view of one of the en- 

 gines when looking towards the boiler, with part of the boat in 

 section. Each engine consists of two inverted cylinders, a a, mounted 

 upon four strong wrought iron columns, b b, &c, which are secured at 

 the lower ends to the foundation plate c, and passing through suitable 

 boxes on the sides of the cylinders, and secured by means of nuts at 

 their upper ends immediately to the. entablature plate and crank 

 pedestals, d, above. The cylinders stand "athwart ships " with their 

 stuffing boxes, e e, looking downwards, and at such a height from the 

 bottom of the vessel as to allow the main cross bar, ff which con- 

 nects together the two piston rods, g g, to work the full length of its 

 stroke below them : the stuffing boxes are made double ; that is, they 

 have a space for packing, both top and bottom, and are fitted with 

 self-acting oil cups for lubricating the rods : /;, is a long connecting 

 rod, by means of which the power is transmitted directly from the 

 main cross bar below, to the crank, i, above the cylinders. In order 

 to ensure an equable action of the two piston rods and their con- 

 necting cross bar, they are further secured and made to work uni- 

 formly together, by means of a strong cast iron vibrating frame 

 forming part of the parallel motion, and which, with side levers, K K, 

 serves also to work the air-pump, /, as well as the feed pump, n, bilge 

 and brine pumps. The paddle shafts, p, wheels, and bearings, are 

 constructed in the usual manner. The slide valves are of the usual, 

 D, form. The condenser, m, is placed immediately underneath the 

 slide valve case, and the air pump, foot and discharge valves, are ar- 

 ranged as shown, being very similar to those of the ordinary side 

 lever engines. The connection between the air pump and condenser 

 is underneath the foundation plate, r; o, is the hot-well from which 

 the waste water is discharged by an overflow pipe through the ves- 

 sel's side in the usual way. The cross forming the support of the 

 side levers is of wrought iron. When working, these engines are re- 

 markably steady, there not being the slightest perceptible tendency to 

 motion in any part of the framing. It is well known that in all recipro- 

 cating engines, of whatever form or construction, the parts of the en- 

 gine subject to the greatest strain, are those which lie between the point at 

 which the cylinder is secured, and the centre of the crank shaft, to which 

 the power of the engine is communicated; hence in this engi- ,the onlv 

 portion of the framing through which the power of tlit engine is 

 transmitted, is from s to 8, and there is no other part of the engine 

 framing whatever subject to the strain of its power, except the short 

 space intervening these two points. The elevated position of the cy- 

 linders also secures them from liability to water from the boilers, as 

 they are at a higher level than the water line ; and accidents from 

 the above cause (to which marine engines are frequently subject) 

 cannot occur. The space occupied by the cylinders is so much above 

 the engine house floor, that there is considerable more space below 

 than in the ordinary engine, to get round about the working parts, 

 which are all below, and occupy a comparatively small space under- 

 neath each set of cylinders; both the upper and lower covers of the 

 cylinders are removable, and by taking off' the upper ones only, there 

 is clear room (without the intervention of the piston rods) to examine 

 and clean the pistons, or adjust them, witLOut disturbing the stuffing 

 boxes below, or uncoupling any further part of the engine. The po- 

 sition of the condenser and air pump is such, as to render them acces- 

 sible on all sides, and the condensers being directly below the slide 

 valves, the exhaustion is rendered more immediate and perfect, by its 



No. 74. Vol. VI.— November, 1843. 



proximity to the openings of the cylinders. The connecting rods are 

 necessarily of great length, and the strain and consequent friction to 

 which engines with short connecting rods are subject, is thereby over- 

 come. The motion of the air pump, as in the side lever engines, is 

 effected upwards whilst the pistons are descending, and the weight of 

 the air pump, bucket, cross head, &c, counterbalance that of the con- 

 necting rod and its appertenances. There is a clear passage between 

 the engines, below the cylinders, on the engine floor, and from this 

 point all the working parts of the engines are within reach of the en- 

 gineer. The saving of weight and space is very great as compared with 

 that of the ordinary marine engine. The total length of room occupied 

 by the above engines and boilers and GO tons of coal, is onlv 34 ft. li in. 

 from bulkhead to bulkhead. The centre of gravity of engines and 

 boilers is not higher than that of the ordinary marine engines, and the 

 saving of weight renders that of engines, boilers, and boat consi- 

 derably lower. 



It may be observed, that in principle of action there is nothing new 

 in these engines, steam of 5 lb. pressure is used in the boiler, and the 

 slide valves cut oft' steam at three-fourths of the stroke. The 

 novelty consists merely in using two inverted cylinders, and in the par- 

 ticular mode of disposing the different parts, and so arranging them, 

 as to confine all the requisites for a more effective and durable engine 

 with the greatest possible saving of weight and space. 



The boilers are of the tubular form, and are the first of the kind 

 made at Liverpool ; they generate an abundance of steam, and have 

 brine pumps attached. An apparatus is fitted to each fire-place for 

 consuming the smoke, upon the principle of admitting heated air. 



The following are some of the principal dimensions, &c, of the 

 engines : — 



Cylinders, 42 in. diameter ; length of stroke, 4 ft. G in. 



Air pump, 33d in. diameter ; length of stroke, 2 ft. Ah in. 



Capacity of condenser, including passage to air pump, 44 cubic ft.; 

 ditto of hot well, 3ii cubic ft. 



Wheel, 23 ft. G in. diameter, to the outside of floats. 



Number of revolutions, 23s. 



Pressure of steam in cylinder, 3| lb. 



The vessel is of iron, and one of the strongest hitherto constructed. 

 She is divided into five compartments by strong water-tight bulk- 

 heads ; her speed by the log during a late trial trip, was 12 knots, 

 (engines making 23 revolutions per minute,) and having 200 tons of 

 coals and cargo, dead weight, on board. 



Dimensions, extreme length, 175 ft.; breadth, 25 ft. ; depth, 1G ft. ; 

 burthen, 573 tons ; draft of water with 400 tons dead weight, 

 lift. 



This vessel is the last of between 50 and GO built by Mr. John 

 Laird, who, we are happy to hear, has now on the stocks an iron fri- 

 gate of 1400 tons for Her Majesty's service, as well as several for the 

 Honourable East India Company, and other parties. 



REMARKS UPON THE PRESENT STATE OF THE HARBOUR 



OF CORK AND THE RIVER LEE. 



Communicated by George White, A.I.C. E., &c. 



The eligibility of Cork as a harbour is so generally known, that it 

 would be superfluous, on the present occasion, to dwell at any length 

 upon its merits. It may not, however, prove uninteresting to take a 

 short notice of its capabilities as a place of refuge. Considering the 

 spaciousness, security, and other advantages which this harbour pos- 

 sesses, it appears difficult to account why Waterford should have 

 received such favour in the late inquiry before a select committee of 

 the House of Commons, instituted fur the purpose of determining the 

 most proper station for a mail communication with the south of Ire- 

 land,' the latter being, as is well known, a bar harbour, having only 

 ten feet water over it at low spring ebbs, besides other disadvantages, 

 with which nautical men are well acquainted. 



Cork is the only place on the south coast of Ireland fit to accom- 

 modate ships of the line, with the exception of Bantry Bay. There 

 are, perhaps, few natural harbours so perfectly devoid of danger; the 



1 See Evidence of William Preston White, Esq., Ilarl otu-mastcr, in the 

 Parliamentary Reports of 1842. 



50 



