40 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[February, 



fall at the bottom of the pipe, would be diminished, and a greater ve- 

 locity than is due to the fall, would be imparted to the fluid in the 

 upper part of the pipe, to produce a mean velocity. The mean be- 

 tween the initial velocity and 32 is 16. Thus, in whatever mode the 

 question is considered, we arrive at the same conclusion, that the ve- 

 locity with which water issues from a vertical pipe, (not exceeding 

 33 feet in length,) is one-half the velocity due to the height of the 

 column. 



We trust we have proved, even to the satisfaction of our corres- 

 pondent, that there are no errors in our reasoning on this subject; 

 and that he was induced to think so, in one case by a misapprehension 

 of our meaning, and in others by a hasty consideration of the main 

 proposition: which appears, though in reality it does not, to deviate 

 from the recognised laws of hydrodynamics. The theory of the flow 

 of water through pipes well deserves a more full consideration than 

 we have now time or space to bestow upon it, and to which we shall 

 probably return. 



JAMES NASMYTH'S PATENT DIRECT ACTION STEAM 

 FORGE HAMMER. 



The truly valuable qualities possessed by wrought iron as the ma- 

 terial of all others the best adapted to withstand force, has rendered 

 its use as a mechanical agent almost universal, so important are the 

 purposes it serves in enabling man to combat with the elements, and 

 as it were bend them to his will, that we may almost measure the 

 progress of civilization in any nation by the quantity of that inesti- 

 mable material they convert to their use ; hence it is that Great Bri- 

 tain owes no small portion of her power, wealth, and mechanical 

 supremacy to her superior knowledge of the use and capabilities of 

 this the most serviceable of all substances. 



National improvement is always indicated and accompanied by 

 increased consumption (by reason of increased application) of wrought 

 iron ; by its use man first merges from the savage state, and by its 

 extended employment the most civilized nations not only maintain, 

 but advance in their improvement. It is, perhaps, unnecessary here 

 to remark how entirely we are indebted to wrought iron for the ser- 

 vices of the steam engine ; and its innumerable progeny of happy 

 results, to say nothing of railways and steam vessels, in the very hulls 

 of which, as well as in other ships, it is rapidly manifesting its su- 

 periority over wood, and so giving to the world another magnificent 

 evidence of its all but universality of application. Hence it is that 

 few mechanical improvements are of more real importance than those 

 which relate to the manufacture of wrought iron, not only in respect 

 to its production in the first instance, but also to our increased facili- 

 ties, and means of working it into such forms as may be rendered 

 desirable and necessary. 



By a property almost peculiar to wrought iron, namely its all but 

 unmeltableness, its applications would have been very limited, by rea- 

 son of the difficulty we should have experienced in fashioning it into 

 any required form, but by another peculiarity, namely its capability 

 of being welded, we have the loss of convenience arising from its 

 unmeltableness more than made up to us, and where we add to this 

 its extreme malleability, by which property and by the assistance of 

 heat, it is capable of being forged into any required form, our com- 

 mand over it is only limited by our means of applying the requisite 

 force, whether by compression, as in the case of the process of rolling, 

 or by blows, as in the case of forging by the hammer ; this latter pro- 

 cess being by far the most important, not only in respect to its afford- 

 ing us the means of giving to masses of wrought iron the requisite 

 shape and form, but also, when the process of hammering is carried on 

 with due energy, while the iron is at a welding heat, the effect of such 

 hammering is productive of a most important improvement in the 

 quality of the iron, as regards its tenacity and consequent capability 

 of resisting strains without the risk of fracture, this gain of strength 



arising from the more intimate contact or union brought about between 

 the particles of the iron, by reason of the more perfect expulsion of 

 all those impurities which otherwise, by separating the particles or 

 fibres of the iron, so impair its strength. Hence we have one of the 

 many important reasons why it is so desirable that we should have the 

 means of hammering iron when at the proper welding heat, with ail 

 due energy, whatever be the size or form of the mass in question. 



The great success which has attended the application of the steam 

 engine in the case of steam ships, and in other instances, has pro- 

 duced a demand for enormous forgings of wrought iron, such as paddle 

 shafts, cranks, &c. that no small difficulty is now felt in the execution 

 of large parts of them, having attained to such a magnitude as to be 

 all but beyond the power and capability of the largest forge hammers 

 to execute them. 



The approach of this point of ultimate capability has long been felt, 

 not only by the vast difficulty and expence by the ordinary means, 

 such enormous forgings being so frequently attended by the destruction 

 of the machinery employed, but also by the frequent occurrence of 

 unsoundness being the certain result of inadequate means, and the 

 exceeding the limits and capabilities of the machinery hitherto em- 

 ployed for the purpose, arising from a defect inherent in the principle 

 on which such machinery has been constructed, the evils of which 

 have been rendered more and more apparent by every successive 

 attempt to enlarge the apparatus, with a view to endeavour to enable 

 it to cope with the increase in the magnitude of the forgings it was 

 required to execute. 



It was with the view to remove those defects in the principle on which 

 such forge hammers were constructed, and to produce such a hammer 

 as should, in the most simple manner, attain all that was desirable in 

 our means of forging the very largest class of work, and that in a 

 manner infinitely more convenient, perfect, and economical, that led 

 me to contrive my direct action steam hammer, which I shall now pro- 

 ceed to describe, and which has realized my most sanguine expec- 

 tations of its advantages. 



In order to give such of my readers as are not minutely acquainted 

 with the subject, a more clear view of the advantages possessed by 

 this direct action steam hammer over those of forge hammers of the 

 ordinary construction, I must refer them to Fig. 1, which is intended 

 to represent a forge hammer of the largest class, and generally 

 arranged according to the most improved principle. According to 

 the scale on which this sketch is made out, such a hammer would be 

 fully what is called a seven ton hammer, and consequently adapted 

 (so far as its principles of construction will permit) for the execution 

 of the largest class of work. 



One chief and universal feature in all such hammers, is, that the 

 power which causes them to rise and fall, and so give out blows on 

 the work on the anvil, consists of rotary motion, which originating in 

 the rectilinear motion of the piston of the steam engine, is conveyed 

 to the hammer by and through the medium of revolving shafts, 

 wheels, &c, and finally reconverted into its original up and down 

 motion by means of the cam wheel, marked D in the sketch ; thus, by 

 a very roundabout course we have brought our power back again 

 into the form it first existed, namely, rectilinear motion, or as nearly 

 so as the radial action of the hammer will permit. And what advan- 

 tage have we obtained by causing our power to travel to its object by 

 such a roundabout course ? none that I ever could see ; and as to the 

 disadvantages, they are many and most serious. In the first place, 

 there is great loss of power, on account of the very unfavourable 

 manner in which the momentum of the fly-wheel on the cam shaft D 

 communicates its motion to the helve of the hammer, by a jolting 

 action most unfavourable to the economical communication of power; 

 add to which the vast space of the forge shop, occupied by all the 

 intermediate apparatus of a complete steam engine, with its requisite 

 fly-wheels, shafts, beams, and very costly foundations, which, in order 

 to endeavour to maintain the apparatus in due order, has to be made 

 of more than ordinary substantiality ; so much so that, to resist the 

 destructive effect of the vibration given to the entire machinery by 

 the action of the hammer, the foundations have to be made so solid 



