i i OK 



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But whatever be their mod* of operation, the fact is certain that 

 blisters often prove more extensivery beneficial than could have been 

 isjshlir- J from the limited surfact on which they act, and from the 

 very s^chl discharge they induce. Though, as already stated, they an 

 mo*! bsBMsftottsvl W!MD 4bs) influtttiMtioii u onlcJ in tsftrticulw unno 

 or in part of an organ, rat they an by no means without advantage in 

 oases ttTwhirh the system it nnenlly and deeply involved; but then 

 benefit can only be obtained from them after bleeding, purging, and 

 other eracuanU hav* lisnnii or subdued the general action of the 

 system. In this case they often complete sod render permanent the 

 bensot derived from the preceding 



For the reatnn already assigned, they are moat commonly employed 

 (attar remedial that act powerfully on the general system) in pneumonia 

 (inflammation of the lung), in gastritis (inflammation of the atomaoh), 

 in hr|.utu (inflammation of the liver), in phreniti* (inflammation of 

 the brain), and so on ; but there are diseases of the nervous system in 

 which they are decidedly ueeful, as in spasmodic affections attended 



but without infUmmation, in the paroxysms of angina 

 of spasmodic asthma, in epilepsy, catalepsy, hysteria, 

 paralysis, Ac. 



Benefit is enmirthntt derived from the application of blisters through 

 their H""****-*" and direct action as stimulants, chiefly in full habit*, 

 in which languor i* the coosequence of over-distension. In these oases 

 they excite the whole system, and produce an exhilarating effect. A 

 gantlsmsn once highly distinguished at the bar, and of brilliant con- 

 vivial powers, always applied a blister when he wished to shine in 

 either sphere, and the effect was produced as soon as the warmth in 

 the part began. Ifany persons, even though they feel acutely the pain 

 produced by busters, declare that the relief from the previous languor 

 eomrterbaUnoBs all their snflhringa, 



The application of a blister is sometimes successfully employed as a 

 i of directly lessening pain. The excitement of one pain diminishes 

 relief affo 



the 



afforded in tooth-ache and other painful 



anna and in some irritable states of the system 



extreme excitement and Buffering. 



previous employment of the appropriate remedies for soothing the 

 irritable state of the system, the beneficial effect of blisters may be 

 obtained even in constitutions thus predisposed to irritation from the 

 operation of this remedy, which constantly produces good or bad effects, 

 just as ita application is well or ill timed. One painful affection occa- 

 sionally induced (strangury) is effectually relieved by on anodyne 

 injection thrown into the rectum, consisting of four or six ounces of 

 thin tepid gruel, with thirty or forty drops of laudanum. 



BLOCK (German, Bleett ; Dutch, Matte* ; Swedish, Sttppi-bloct ; 

 French, Poulie; Italian, BoteUi; Spanish, Sfotuoa ; Portuguese, 

 Mmiloa i Buss, Hluti), an instrument generally made of wood, but 

 sometimes of iron. It is much employed in the rigging of ships to 

 give facility to the raising or lowering of the masts, yards, and sails, 

 sad for such other purposes aa require and admit of the application of 

 the pulley a block, as used on board of ships, being simply a pulley 

 in the greater part of ita modifications. One description of Mocks, to 

 which the name of dead-eyes has been given, is not a pulley, being 

 unprovided with sheaves. These dead-eyes are used for setting up and 

 fastening the shrouds and other standing rigging of the ship, while 

 sheaved blocks are used for the running rigging. The more usual form 

 of blocks of both descriptions is that of an oval spheroid, flattened at 

 opposite sides. Dead-eyes are made out of one piece of wood, pierced 

 with the requisite number of holes, through which the standing rigging 

 is (issxirt Single sheaved blocks are made up of three distinct parts, 

 namely, the shell, the sheave, and the pin which serves as an axis 

 round which the sheave revolves. Some blocks are made with two, 

 and others with three, and even four sheaves, which all revolve on 

 the esme pin or axis, and consequently parallel to each other, in 

 9 chambers formed for that purpose in the shell of thu Mock. 

 i in all their varieties are used also for the pur|>ose of raising 

 in every department of mechanics and constructive ope- 



The construction of blocks would seem to be a very simple opera- 

 tion, soon as any man accustomed to work in wood could perform with 

 facility and accuracy; but this in practice is nt t'oun.l to be the case, 

 as the part* must be fashioned and fitted together with the greatest 

 possible accuracy, in order to insure their easy working when put 

 logethsr a circumstance of considerable importance iu the manage- 

 ment of a shin. Kor thin reason, block-making has long formed a 

 substantive branch of manufacture, and is carried on either by itself, or 

 in conjunction only with mast-msliing 



About 1801, Mr. Brunei succeeded in completing a perfect working 

 model for constructing both the shells and sheaves of b|.,-k-. Tl,i- 

 model bong submitted to the inspection of the Lords of the Admiralty, 

 the invention was at once ad|>ted by government, and Mr. Brunei 

 was engaged to superintend the construction of the requisite machinery 



The 



of machines devised by his inventive genius for the 



formation of the blocks employed in raising burdens, and particularly 

 in the important service of moving the rigging of ships, contains so 

 many ingenious processes for gaining the proposed ends with the 

 utmost accuracy, and, at the same time, with the least possible labour, 

 as to justify the opinion that it constitutes one of the noblest triumphs 

 of mechanical skill ; and, in this article, it is intended to give a brief 

 description of the principal parts of which it is composed. 



The machines may be said to consist of many saws and lathes ; by 

 these the work is performed, from the operation of cutting up a log 

 of timber, to that of polishing the pins on which the pulleys turn ; and 

 motion U communicated to all of them by a single steam-engine. 



A straight saw worked backwards and forwards, horizontally by the 

 engine, cute off in succession different portions transversely from tlie 

 log of timber (elm) which, for this purpose, is made to rest on a table 

 or low bench ; the portions cut off being of the proper lengths for the 

 dimensions of the intended blocks. For the smaller logs a circular 

 saw is used ; it cuU the tree transversely, and consequently its plane is 

 perpendicular to the axis of the latter : the saw is capable of being 

 raised vertically, or moved horizontally at pleasure, in order that it 

 may be made to enter the wood above or below, or on either side. 



After the log has been cut in slices, the Utter are brought to what 

 is called the ripping saw: this is circular; and ita piano standing 

 vertically, in part above the level of the table, it serves to cut the 

 slices into rectangular parallelepipeds. In this state the wood is brought 

 to the boring machine, which may be thus described (the lower figure 

 representing the plan, and the upper a side elevation) : 



The rectangle A B c D represents the surface of a strong table, on 

 which is fixed an iron frame E having three legs ; within these the 

 parallelepiped F is placed between three screw-heads, two of which 

 appear at a a, and it is rendered imtnoveable during the operation by 

 means of the screw 6 ; this last being turned by the iron bar an. cd 

 is one of the borers, which turns on its axis by means of the pulley K, 

 the latter receiving motion from the engine : this borer rests on the 

 frame 11 N, which is capable of being moved towards the frame n 

 by pressing on the end r of the lever p q, so as to turn it about 

 the pivot Q. h k is another borer, which turns on ita axis by means 

 of the pulley B, the latter also receiving motion from the engine: 

 this borer rests on the frame B T, which is capable of being moved 

 towards the frame E by pressing on the handle V \, so as to turn it 

 about the pivot v. 



M d 



The former borer makes the hole for the pin on which the sheaves 

 of the block are to turn : tin- oilier merely makes a perforation at a 

 -put which i* t<> fonii one extremity of the mortUe intcndol to . 

 a sheave. If the block i to contain two or three sheaves. ' 

 to make as many | . the frame HT being capable of moving 



in a direction parallel to i> n. in order that the point of the borer may 

 be placed where the required |>crforaUons are to be made. 



A remarkably ingenious machine is employed to cut the mortises 

 iu which tli.' pulley* are to turn ; and it u hoped that the following cut 

 and description will suffice to render the process intelligible. A B is a 

 representation of the horizontal surface of the table or stage on wliieli 

 the block is placed ; and the diagram above it exhibits a side elf 

 of the acting part of the machine, the pillars and braces which support 

 it being omitted, as they would have concealed, in part, the apparatii*. 

 to is a frame made to contain the Mock A which, in the diagram, has 

 I. ut one mortise ; the block is tightly fitted iu this frame by means of 



w t at one extremity, and the frame is capable of being > 

 along the stage from towards ll,&n much as the whole lengl li of i In- 

 intended mortise. The great screw o D is fixed at one extremity to 



