October 15, 189 1] 



NATURE 



579 



plicated and costly methods should have stood so long, consider- 

 ing that Sir Henry Bessemer's patents have long since expired, 

 and his direct process is open to anyone to adopt. The metal, 

 as tapped from the furnace, in place of being run into ingots, 

 to be afterwards rolled into slabs or billets, is just poured on to 

 the top of a pair of water-cooled rolls placed with their axes 

 in the same horizontal plane. The rolls are caused to revolve, 

 and the molten metal finds its way down between the space left 

 between them, and is thus rolled out into a continuous plate or 

 sheet ; the chill received in passing through the rolls being 

 sufficient to solidify the metal. That the process is possible 

 Sir Henry proved over iforty years ago ; that it may be made 

 commercially successful appeared to be the unanimous opinion 

 of the many competent critics who spoke in the discussion. 

 Under these circumstances it would seem that the only reason 

 why there should not be a radical change in the way of 

 manufacturing steel plates is that the process is open to every 

 one, and, as there are no pa'ent rights to be acquired, it may 

 be worth no one's while to go to the initial expenses of starting 

 a new process just to show competitors how to do the same 

 thing. 



Mr. W. H. White's paper on the shipbuilding material at 

 the Naval Exhibition was a useful and interesting contribution, 

 although not so exhaustive as might have been desired. It 

 would, however, be too much to expect so important a public 

 servant as the Director of Naval Construction to devote his 

 time to writing treatises for technical Societies. What Mr. 

 White has written is of interest. He points out how the work 

 of shipbuilding has been simplified and cheapened by the steel 

 manufacturer, who now rolls many special sections, such as 

 Z bars, channel bars, H bars, T bulbs, and angle bulbs, thus 

 saving a vast amount of building up and riveting in the actual 

 construction of the ship. The increase in the size of plates, 

 both for ship and boiler work, was also pointed out by the 

 author. Two specimens of bjiler plate are shown in the 

 Exhibition, which are both i^ in. thick and respectively 42 ft. 

 long by b\ ft. wide, and 31 ft. long tiy 7^ ft. wide. Another way 

 in which the steelmaker and founder has helped the shipbuilder 

 is in producing complete parts of ships, such as stern frames 

 and stems, especially the spur sems of war vessels, which 

 necessarily have to be of massive construction. In old days, 

 when such parts were made of wrought iron, the forging had to 

 be machined to form the recesses or "rabbets" necessary for 

 the attachment of plating. That was excessively costly work, 

 and in the case of such heavy articles was most difficult to 

 accomplish at all. W'ith steel castings little or no machining 

 is required. Mr. White exhibited a large hull diagram of a 

 ram bow for a recent battle-ship. The part istmade hollow, or 

 rather recessed, and shelves are cast on to receive the plating of 

 the decks, and the attachment of breast hooks, &c. The author 

 also referred to the exhibits of armour plate made at the Ex- 

 hibition, but the subject is toi lengthy for us to go into here, 

 excepting to say that nickel steel has been proved by test to 

 show such good results for armour that some of the secondary 

 armour plating for five first class battle-ships is now being made 

 of that material. 



Mr. W. D. Allen, in his paper, described a forging press, 

 which, although it has been at work for some years at the 

 Bessemer Works in Sheffield, is so ingenious, and so new to 

 most people, that we shall attempt to describe it. The press 

 has the appearance of a steam hammer, and, indeed, there is a 

 steam cylinder at the top, just as in a hammer. The use of the 

 steam, however, is only to raise the tup when the hydraulic 

 pressure is released. The press consists of an anvil block below 

 and a ram above, the work being in a vertical direction. The 

 ram works in a hydraulic cylinder, and is carried through the 

 top end of the latter in the shape of a stout shaft or shank, 

 which may be described as a tail rod to the ram. Attached to this 

 is the piston rod of the steam piston, the latter of course working 

 in its own cylinder. The steam cylinder and hydraulic cylinder 

 are therefore placed tandemwi-e, the latter being underneath. 

 The hydraulic cylinder is supplied with water at pressure by a 

 suitable pump, the barrel of the pump being in direct communi- 

 cation with the hydraulic cylinder, there being no valve of any 

 kind between the two. If we have made our explanation clear, 

 it will be seen that the ram will descend and ascend stroke for 

 stroke with the pump plunger^ (the same water flowing back- 

 wards and forwards continuously), it being remembered that the 



' There are actually two plungers, the pump being of the duplex type ; 

 but this is a detail which does not affect the principle. 



NO. II 46, VOL. 44] 



steam cylinder has always a tendency to lift the ram. Thus, 

 upon the pump making a forward stroke, the water in its barrel 

 is forced into the hydraulic cylinder ; the ram is thus forced 

 down, and gives the necessary squeeze to the work on the anvil. 

 The pump plunger then starts on its return stroke, and so, by 

 enlarging the space in the pump barrel, enables the hydraulic 

 ram to rise and press the water out of the cylinder and back 

 into the pump. The rising of the ram is caused by the lifting 

 action of the steam under the piston ; the latter, it will be 

 remembered, being attached to the ram. Of course the water 

 pressure is sufficient to overcome the steam pressure on the 

 downward stroke. The chief use of this press is to produce 

 work of any given thicknesses within the range of the machine. 

 This end is attained by regulating the volume of water used. 

 The action may be explained as follows. We will suppose, 

 merely for simplicity sake,^ the content of the pump barrel to be 

 one cubic foot, and that of the hydraulic cylinder, when the 

 ram is at the full extent of its stroke, to be two cubic feet. We 

 will neglect the connecting pipe between the two, as that is not 

 a variable and does not affisct the principle. If there be ad- 

 mitted to the pump but one cubic foot of water as the plunger 

 moves forward, it will drive all this water (omitting clearance) 

 into the hydraulic cylinder, and the ram would therefore only 

 descend one half its stroke. If the stroke were two feet the 

 travel would be 12 inches, whilst there would be 12 inches 

 of space between the anvil and the lower side of the 

 squeezing tool on the end of the ram. Objects of 12 inches, 

 or above 12 inches in thickness, could therefore be forged. 

 If, however, an article 6 inches thick had to be worked, 

 another half cubic foot of water would have to be admitted. As 

 the pump barrel would only accommodate one cubic foot of 

 water, the extra half cubic foot would remain permanently in 

 the hydraulic cylinder, and the ram would therefore not go, by 

 six inches, to the top of its stroke ; in other words, the traverse 

 of the ram would be carried six inches nearer the anvil. It will 

 be remembered that the upward movement of the ram is effected 

 by the steam cylinder, which is powerful enough to lift the dead 

 weight of the ram, but is overcome by the hydraulic pressure. 

 It will be seen that by regulating the volume of water in 

 the machine, the ram — although always making the same 

 length of stroke — can be kept working at any given distance 

 from the anvil : the ram and pump-plunger making stroke for 

 stroke as the water flows backwards and forwards between the 

 barrel of the pump and hydraulic cylinder. The device is no 

 less important than ingenious. In ordinary forging, reliance 

 has to be placed for accuracy of work on the skill of the work- 

 man. It is surprising how near perfection a good forgeman 

 will arrive by constant practice. Such men are necessarily 

 scarce, and as a consequence very highly paid, but even the 

 nearest approximation of eye and hastily applied callipers, 

 with the chance of getting a little too much work on at the last 

 minute, cannot equal the absolutely correct results of this auto- 

 matic system. There is a very ingenious valve for regulating 

 the admission of water to fine gradations, so as to get work 

 accurately to gauge, but we have, perhaps, given enough descrip- 

 tion of mechanism for one article. 



Mr. Carulla's paper was interesting and suggestive. He was 

 engaged in melting Bessemer scrap in pots when a crucible 

 gave way in the furnace just as fusion was neariy complete, the 

 greater part of the contents flowing out into the fire. The 

 melter was just bringing the crucible out, and, instead of finding 

 an empty broken crucible in the tongs, he discovered a number of 

 shells corresponding in shape with the pieces originally charged, 

 but quite hollow. This was Mr. Carulla's unaccounted for 

 phenomenon, upon which he invited an explanation. This dis- 

 cussion was not satisfactory, and it was evident that those who 

 spoke had not prepared their ideas. This was not the fault of 

 the speakers, but of the way in which the business of these 

 meetings is carried on. The remark applies not only to the 

 Iron and Steel Institute, but to most of the technical Societies 

 of the same class. When a meeting is held, a mass of papers 

 are brought forward and read more or less hurriedly, and 

 members get up to make such remarks as may occur to them on 

 the spur of the moment. It is needless to point out that no 

 satisfactory discussion of matters involving scientific principles 

 can be carried on in this way. Mr. Carulla's paper is, as we 

 have said, suggestive, and a complete explanation of the facts 

 he slates would doubtless lead to most important discoveries in 



' The press ram makes a stroke of 3^ inches, and its diameter is 30 inche?. 

 The total pressure at 3 tons per square inch would be 1700 tons. 



