PRINTING PRESSES. 



1G7 



\iming torn of a square pillar P, two opposite angles of which 

 slide in angular grooves in the tv. u pieces of metal a, 0, 



"" "~" \\hirli -trctdi from tin- frame, and hare adjusting 

 screws, Sec. to tighten them to tin- M|iiare pillar. 



The incrh.-mism or combination ol 1< \<rs hy which 

 -rent of the plattin is produced, is shown at 

 HIKLMN. The IUM'II lever LAIN moving round a 

 strong holt at N, passes through a fork in the frame at 

 \. The other end L of the lever passes through an 

 aperture between the vertical bars at m, and its central 

 part at M has a stout pivot or gudgeon cast upon it, 

 which goes into collars at the top of the square pillar 

 I', kept together by strong bolts. Two links L, /, one 

 being on each side, connect the main lever with the se- 

 cond lever n, o, moving on a fixed centre at o in the 

 great frame. Another link p is connected by an uni- 

 versal joint to n at one end, and at the other to the 

 lever or handle II, at which the pressman works. This 

 handle turns on a fixed centre pin extended from the 

 great frame. 



On the top of the vertical bars at n is placed the 

 fulcrum/^ of the counter-lever g,J', h, which carries an 

 adjustible counter-weight W, the end g being united 

 by a link to the end L of the main lever. The use of 

 this counter-weight is to raise the main lever into its 

 acting position, after the handle II has been let go by 

 the pressman. 



Barclay's American Press. 



This press has been lately introduced into this coun- 

 m try from America, by Mr. David Barclay, its inventor. 

 The great parts of the machine it is unnecessary to re- 

 present, as it is only the method of giving the pressure 

 to the plattin that gives it its chief interest. We have, 

 therefore, represented this in Fig. 7, where A, A re- 

 present the two upper inclined plates, and B, B the 

 under one, which is fixed on the top of the plat- 

 tin, while the upper one A is fixed to the head of the 

 press. A wedge W, made of well-hardened steel, is 

 fixed to the end of the lever handle of the press, so 

 that when this handle is pulled, the wedge W is forced 

 between two steel rollers C, D, so as to roll them along 

 between the two inclined steel plates, and consequent- 

 ly leave the lower plate B and the plattin to descend. 

 The left hand figure represents the rollers when the 

 plattin is pressed down ; and the right hand one the 

 same rollers when the plattin has risen to its place of 

 rest. The lever handle H moves round n as a fulcrum, 

 and by increasing or diminishing a connecting link the 

 required force is obtained. 



As the rollers are necessarily above the centre of the 

 plattin, the plattin is guided in its ascent and descent 

 by two metallic bars, not very distant from its margin, 

 and at the top of each of these bars there is a spiral 

 spring, which bears against the top of the frame, and 

 by balancing the weight ot the plattin, keeps it always 

 clear above the tympan when the handle is at rest. 



Welh's Printing Press. 



This press, which has been recently constructed in 

 America by Mr. Wells of Hartford, has been described 

 by the late Professor Fisher. The plates, drawing, and 

 description of it are taken from Ferguson's Lecture*, vol. 

 ii. p. 265. " The frame is of iron, cast (with the ex- 

 ception of the feet) in a single piece ; and is of such 

 form and dimensions as to be incapable of springing 

 while the press is in operation. The plattin (4) is of 



>n, and is of the dimensions of an entire form. I'riniing 

 The circular projection in the middle, with MX radiat- 

 ing pieces, gives it an ample degree of firmne*. T.'.L- 

 plattin is immediately acted on by bringing nearly into cccctxvin. 

 a straight line the two main lever* (6) and (17.) These p.g. %. 

 levers, in presses of the medium *ize, are fifteen inches 

 each in length, ami in the position represented in the 

 figure, which is that of the greatest obliquity, they 

 want two and a quarter inches at their point of contact 

 of being straight. The lower end of each lever u four 

 inches broad, and is rounded off into a portion of a cy- 

 lindrical surface of half an inch radiui. A piece of steel 

 fixed within the circular projection in the middle of 

 the plafin has a hollow bush or bed of corresponding 

 figure; in this the lower end of the lever (17) is set. 

 The upper end of this lever is hollowed out in the same 

 manner to receive the lower end of (6), and the upper 

 end of (6) to receive a projection from the under side of 

 the top of the frame. At (5) there is a provision for rais- 

 ing or lowering this projection by slips of sheet iron 

 or tin, and thus adjusting the position of the levers to 

 the best working state. The ends of the levers and 

 the beds in which they rest are overlaid with steel, and 

 the beds are so contrived as permanently to retain a 

 small quantity of oil. (9) is a spindle of wrought iron, 

 fastened at the upper end by a screw and nut to the 

 shorter arm of the balance lever (7), and branching 

 below into three parts, each of which is attached by 

 an adjusting screw to the plattin. This answers the 

 double purpose of keeping the plattin steady, and ena- 

 bling the weight (18) attached to the longer arm of 

 the lever (7) to lift the plattin and carry back the bar 

 immediately after each pull. The plattin is still farther 

 guided by lateral projections which run in grooves 

 connected with the cheeks of the press. 



The mode in which the movement of the working 

 bar (12) is transmitted to the main levers, will be beat 

 understood from Pig. 15, which is a representation of 

 the parts 11, 12, 13, and 15, as they would appear to 

 an eye looking down upon the press from above. The 

 bar BA (the lever worked with the hand) is inserted 

 into a strong cast iron roller (13) which turns in sockets 

 secured to the right cheek of the press. From thia 

 roller, about 6 inches above the bar, proceeds an arm 

 AC, three inches in length, and to the extremity of 

 this is connected by a joint the driving lever CD, 21 

 inches long. The extremity D is connected in a simi- 

 lar way with the iron rod EF ; one end slides in a 

 pewter guide, (represented by 10 in Fig. 14,) while 

 the other end is fastened by a hook and eye to the 

 upper main lever (6) at the distance of an inch from 

 the bottom. (16) is a bar check, which limits the 

 revolution of the bar to a precise arc. The carriage 

 part of the press, which stands in front of the upright 

 iron frame, presents nothing materially different from 

 the Columbian press, and will not require a particular 

 description. 



The operation of the mechanism will now, it is be- 

 lieved, be sufficiently apparent. W T hen the bar BA is 

 brought round, the roller A and the arm AC are made 

 to turn with it ; this drives forward the lever CD, and 

 this in its turn gives motion to EF, which, by means of 

 the elbow at F, brings the two main levers ((>) and (17) 

 towards the position of a straight line. As the move- 

 ment of the bar is continued, the mechanical advan- 

 tage not only increases from the gradual approach of 

 the two mam levers to a vertical position, but from 

 the approach of ACACD towards a straight line. The 

 combination is therefore one which is eminently adapt- 



