274 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[July, 



it reckoning every half inch the float riws, eijual to an augmentation of the 

 elasticity of the s'.eam, coresponJing to the supporting a column of mercury 

 an inch high, Ijecausc the surface has sunk as much in one leg as it has 

 risen in the other. Soliler a small copper fossct pipe, to fit the copper com- 

 municating tube of the harometer, inio the eduction pipe, twelve inches under 

 the fossei of the blowing valve, and on the opposite side of the eduction pipe ; 

 place the harometer in the door way to the condenser, on the further side 

 from the plug tree, so that the engine man may see it when at his station ; 

 join the copper tube to it, by pouring melted sealing wax into the copper 

 cup at to]! ; fill the short leg of the barometer wilh mercury, within four or 

 live inches of its top ; and put a light float in it, long enough to reach to the 

 top of its frame. 



49. Fill the condenser cistern ; shut the lower regulators ; and (there being 

 no steam in the cylinder, or its communication with the boiler being cut ofl',) 

 take off the bonnet or cover of the exhaustion rei^ulator; shut that regula- 

 tor ; and work the air pump by means of the brake. If then you find that 

 air enters by the regulator, pour some water on it, and continue pumping 

 until you have raised the b;\rometer, i. e. sunk its float to twenty-seven or 

 twenty-eight inches ; leave off pumping, and observe if the vacuum con- 

 tinues good, or is a long time in being destroyed. If it loses fast, seek for the 

 leaks which must be somewhere in the eduction pipe, and will make a noise 

 if touched with a wet hand. If the condenser moves by the pumping secure 

 it. After having cured these leaks, you may try the tightness of the cylinder 

 by staking the working beam, so that the piston cannot descend : then take 

 the cover off the cylinder, open the exhaustion regulator, and shut the steam 

 regulator. On beginning to pump you will perceive if the piston be tight ; if 

 it is not, it may be beat a little, and some water being thrown upon it, and on 

 the steam regulator, whatever air enters must be by leaks, which must be 

 sought for, and cured, by screwing, or caulking in with oakum. — N. B. A 

 critical tightness in the piston cannot be obtained until the engine has gone 

 a few days, without beating its stuffing too hard, to permit the engine to 

 move easily. When no more leaks can be detected in this way, tlie steam 

 must be admitted, and the same examination made as before. 



50. The piston chain must be so adjusted that the piston shall descend 

 within one inch of the lead ring at the bottom, when the springs are pressed 

 down by the catch pins; and that, when it is at its highest range, its 

 upper edge shall be level with the square opening at top ; so that no water 

 may lodge there, but may run down the perpendicular pipe ; and the engine 

 should always be made to work fnll stroke ; otherwise it will spoil the cylin- 

 der.— A collar of soft rope must be lapt round the piston rod, under the lid, 

 to prevent the piston striking it, if it should rise with a jump; and if the cap 

 of the piston rod does not touch the gland of the stuffing box, wlien thecatch 

 pins have pressed down the springs above, a collar of iron must be fitted on 

 the rod, to make up the deficiency, and to help to save the blow, if the chains 

 should give way and the piston fall. For though it should break the cylin- 

 der lid. that is much smaller damage than the bottom of the cylinder would 

 be, as the lid may be clasped or otherwise mended. 



51. There ought to be elects, or strong brackets of wood, firmly bolted to 

 the dry pump rods ; and beams should be put across the pit, at proper dis- 

 tances, to receive those elects, in case of the accident of their breaking. 



52. After the engine has been set to work, and has gone a few hours, the 

 holding down screws must be screwed tight, and so from time to time as they 

 become slack ; and in like manner all the other screws about the cylinder or 

 nozzles must be screwed up as they slacken ; and the joints be caulked and 

 puttied where they require it. 



DiKECTiONS FOR WORKING THE ENGINE. 



53. It being necessary , (say Messrs. Boulton and Watt,) that the uses of 

 he several regulators be thor ovghly mlerstood by those who attend to the 



engine, we shall begin by describing them. In the lower nozzle, or regulator 

 box, are two regulating valves. When the upper one is opened, it admits the 

 steam from the perpendicular steam pipe into the cylinder, below the piston, 

 and thereby permits the piston to ascend ; or, in the engine man's phrase, 

 allows the engine " to go out of the house." This regulator we call the "steam 

 regulator." The lower re gulator, which is placed in the bottom of the nozzle 

 or regulator box, when open, sutlers the steam to pass from the cylinder into 

 the air pump of the condenser; and thereby a vacuum is produced in the 

 cylinder. This valve is called the " exhaustion regulator." There is a third 

 regulating valve, called the " top regulator," placed in the cross pipe at the 

 upper end of the perpendicular steam pipe. This serves to proportion the 

 quantity of steam from the boiler to the load of the engine ; so that when the 

 load is less than ten pounds and a half on the inch, the steam in the upper 

 part of the cylinder, which presses upon the piston, may be less dense, or 

 weaker, than the steam in the boiler ; and consequently a smaller quantity 

 of it be employed to do the work, than wruld be required were the engine 

 fully loaded. This regulation may be efTecled in two ways; either by oiien- 

 ing the top regulator fully, at the beginning of the stroke, and shutting it 

 before the piston arrives at the bottom : or by opening it so far as just to give 



the piston a sufficient velocity, and keeping it open until the end of the 

 stroke. 



!)i. The engine being supposed to be in motion, the operation of these valves 

 will be as follows. When the piston is at the bottom of the cylinder, and the 

 exhaustion regulator is shut, if the steam regulator be opened, the steam will 

 pass tlirough the perpendicular steam pipe, and that regulator, from the 

 upper part of the cylinder above the piston into the lower part of the cylin- 

 der, below the piston; and the steam thereby becoming equally strong, or 

 dense, above the piston and below it, will give no resistance to the ascent of 

 the pistcin, which, therefore, will be pulled up by the superior weight at the 

 pump end of the working beam. When the piston has reached the upper end 

 of the cylinder, the steam regulator must be shut ; the exhaustion regulator 

 opened fully ; and, at the same instant, the top regulator opened so tar as to 

 admit the proper quantity of steam,— the degree of this opening must be de- 

 termined by experience, — the steam contained below the piston will then rush 

 from the cylinder, through the e-xhauslion regulator into the vacuum, or 

 empty space in the eduction pipe, where it will meet the jet or stream of in- 

 jection water, which «ill instantly condense, or reduce it to water; and 

 thereby exhaust, or empty the cylinder of steam. — The steam in the upper 

 part of the cylinder being no longer balanced by steam below the piston will 

 press upon it by its elasticity, and the piston will begin its motion downwards. 

 As it moves downwards, the steam in the upper part of the cylinder will 

 become less dense than that in the boiler, which will therefore enter the upper 

 part of the cylinder by the opening of the top regulator, and will maintain 

 the steam in that part of the cylinder in a proper degree of density, or 

 strength, to give the necessary velocity to the piston, and to press it to the 

 bottom of the cylinder. But if the engine be underloaded, it will be neces- 

 sary to shut the top regulator a little before the piston is at the end of its 

 stroke. It has been observed, that the precise time at which the top regula- 

 tor should be shut must be determined by experience, no certain rule can be 

 given, because it depends upon the degree to which it is opened, and upon the 

 load of the engine at the time ; but it must always be shut sooner than the 

 exhaustion regulator, which is kept open to the end uf the stroke. — The in- 

 jection valve should be opened a little before the exhaustion regulator, that 

 the exhaustion pipe and the water, remaining from the last stroke, may be 

 cold when the steam enters; by which means the condensation will be per- 

 formed more suddenly. The injection should be shut very soon after the 

 piston begins to descend ; observing, however, to let it play so long, that the 

 degree of vacuum, shown by the barometer, may be greater in the latter part 

 of the stroke than in the beginning of it. The opening or adjutage, of the 

 injection pipe must be proportioned to the load of the engine ; so that the 

 proper quantity of water may enter in abuut one second of time ; and as the 

 load increases, the opening must be enlarged. 



55. The eduction pipe serves to convey the injection water, and condensed 

 steam, to the fuot of the air pump of the condenser ; the injection pipe enters 

 it at its knee, and spouts along the horizontal pirt of it ; and from its side 

 issues the blowing pipe, the use of which is to empty the eduction pipe of air 

 and water when the engine is put into motion, after it has been stopped at 

 any time. At the bottom of the eduction pipe is a hinged valve, or clack, 

 which permits the water and air to pass into the air pump ; but prevents it 

 from returning. This valve should be very tight ; it is called the valve of 

 the eduction pipe toot. 



56. The air pump is the lowermost and widest pump of the condenser. 

 When the steam enters the eduction pipe, it spoils the vacuum for an instant ; 

 and then presses upon the water in the lower part of the eduction pipe, and 

 forces a part of it into the air pump. As the piston of the cylinder descends, 

 the bucket of the air pump ascends ; carries up along with it the hot water 

 which was above it ; and leaves a vacuum under it ; into which the remain- 

 ing injection water enters— first because it stands higher in the eduction pipe 

 than in the air pump; and secondly, because the vacuum, in the eduction 

 pipe, is not quite so complete as in the air pump. — The water, raised by the 

 air pump bucket, passes through the clack of the hot water pump, into the 

 vacuum produced by the rising of the bucket of that pump ; which is raised 

 at the same time with the bucket of the air pump; and no part of it will 

 come out at the valves, or the lid, or the cover of the air pump, unless the 

 bucket of the hot water pump is not tight; or unless an overplus quantity of 

 water entersthe eduction pipe, or condenser, by leaks ; for if there be a suffi- 

 ciently empty space left by the bucket of the hotwatcr pump,it!s evidentthat 

 the water will rush into it, andfill that space before it can open the valves on 

 the lid ; which valves are kept shut by the pressure of the atmosphere, so 

 long as there is any degree of vacuum in the upper part of the air pump, or 

 that part of the hot water pump which communicates with it. — When the 

 air pump bucket descends, it leaves a vacuum behind it, because the water is 

 detained by the hot water pump , and the water in the lower part of the air 

 pump passes through the valves of the bucket, which lilts it up the next 

 stroke as before. — The hot water pump raises the water high enough to let 

 it run into the boiler by the feed pipe, or into a reservoir to be cooled, and so 

 to serve the purpose of injection the second time. 



57, The barometer serves to shew the degree, to which the cylinder is ex- 



