166 



PRINTING PRESSES. 



Printing 

 Tresses. 



Heine's 

 improve- 

 ment 

 on the 

 Stanhope 

 press. 



Keir's im- 

 proved 

 Stanhope 

 presses. 



Midhurst's 



improved 



press. 



lluthven's 



printing 



press. 



side, and is regulated by the screw. By this means the 

 descent of the plattin may be increased or diminished. 

 The surface of the plattin is turned so as to be perfect- 

 ly plane. 



Since the invention of this press various improve- 

 ments have been made upon it, one of which by M. de 

 Heine has been secured by a patent. In place of the 

 screw he has substituted a spiral or curved inclined 

 plane, which is fixed to the head of the press. On the 

 upper end of the spindle is fixed a cross arm, which, 

 acting against the fixed inclined plane, performs the 

 functions of the screw. The advantage of this substi- 

 tution is, that the acting faces admit of being made of 

 hardened steel. 



The Stanhope press has likewise received several va- 

 luable improvements from Mr. Peter Keir. He forms 

 the slider d, by boring out a cylindrical hole down the 

 centre of the press, and he fits accurately into this a 

 cylinder, to the lower end of which is fastened the 

 plattin. A flat side is made to the cylinder, which is 

 prevented from turning round by a bar of iron screw- 

 ed across the two cheeks, and bearing against the flat 

 side of the cylinder. Mr. Keir has also improved the 

 lever apparatus. By a screw cut into the lower end of 

 the spindle M, and fitted into a nut, the spindle is made 

 to rise and fall through a space equal to the descent of 

 the great screw in the same time. The connecting 

 rod O is thus made to pull in a horizontal plane, while 

 in the old construction one end remains level when the 

 other descends, the consequence of which is an unequal 

 wearing of the joints. 



An improvement on the printing press has also been 

 made by Mr. Midhurst. It resembles generally the 

 common printing press ; but the plattin is the size of a 

 sheet, and in place of a screw is used a plain spindle, 

 on the lower part of which, just above the bar, is fixed 

 a circular plate, which affords steps for the points of 

 two iron rods, which extend up to the head, and are 

 supported in that place by their points entering soc- 

 kets. These rods have an inclined position when the 

 plattin is raised, although both the ends of them are at 

 the same distance from the centre of the spindle ; but 

 when the spindle is turned by the bar, the circular 

 plate in which the lower points of the iron rods rest, 

 moves round in a circle, and the upper ends remain sta- 

 tionary. Hence they come towards a vertical position, 

 and by this motion the spindle and plattin are made 

 to descend. The advantage of this contrivance is, that 

 there is little friction, and that this power is immensely 

 great when the rods come nearly parallel to the spin- 

 dle. 



Ruthven's Printing Press. 



This very ingenious piece of mechanism, invented in 

 1813 by Mr. Ruthven, printer in Edinburgh, possesses 

 advantages which render it in many respects superior 

 to any other. In all the presses which we have de- 

 scribed, the motion of the carriage containing all the 

 types and frame below the plattm must be considered 

 as a piece of mechanism which should if possible be 

 avoided. To remove this necessity seems to have been 

 the primary object of Mr. Ruthven. He seems to have 

 resolved to keep the form of types fixed, and to make 

 the plattin moveable ; and of course the whole mecha- 



Printing 

 Presses. 



nism of his press acquires its character from this funda- 

 mental improvement. 



The construction of this press will be best understood 

 from Plate CCCCLXVIII. Figs. 4 and 5, where AA 

 is the bed which sustains the form of types which re- fig?. 4>, 5 

 mains fixed in the same position. This bed is sup- 

 ported by a framing of cast iron, as shown in the fi- 

 gure. The plattin is shown at PP, and is joined to a 

 strong cast iron bar MM by screws s, s. At the ends 

 of this bar there are strong iron bolts b, b, secured by 

 screw nuts at the top. These bolts terminate below in 

 heads or projecting pieces, which fit exactly the hooks 

 or clutches at E, E. At each of the remotest ends of 

 the bar MM is fixed an oval steel spring, and on the 

 lower ends of each spring are two grooved wheels or 

 rollers, which run on a rail-way, so that the whole 

 plattin may be pushed off the form of types after it has 

 given the pressure, and again brought above it to press 

 the succeeding sheet. These springs have their elas- 

 ticity and form so adjusted, that the lower surface of 

 the plattin is raised above the margin of the tympan, 

 where the springs are not in action. The plattin, 

 therefore, readily moves into its position immediately 

 above the tympan, and as soon as it is pressed down 

 upon the types, the action of the springs raises it above 

 the margin of the tympan, and permits it to be pushed 

 aside by the handle h from the form of types. 



We have already mentioned, that the lower ends of 

 the bolts b, b, which are generally shaped like the 

 frustum of a wedge, go into a hollow of the same form 

 when the plattin is pulled above the types. The ob- 

 ject of this is to lock the plattin to the compound 

 lever * EFGHKL, which, vi-hen moved by the handle 

 H, presses the plattin upon the types. This part of 

 the apparatus consists of two levers DF, DF, moving 

 upon fixed centres at D, D. The clutches, or wedge- 

 shaped cavities, are jointed to these levers near the 

 fulcra D, D, so that when the extremities F, F of the 

 levers DF, DF are pulled down, the clutches are also 

 pulled down, and therefore pull down the plattin to 

 which they are locked. The descent of the ends F, F 

 is produced by a link G united to both, and this link 

 is again joined to another lever, whose fulcrum is at 

 K, while the other end is connected with the handle 

 H, by which the pressure is given. These levers are 

 so arranged, that the maximum force is given when the 

 plattin just begins to touch the tympan. The plattin 

 in Mr. Ruthven's large presses is the size of a full 

 sheet ; and in consequence of the pressure not being 

 propagated from its centre, the pressure over the whole 

 sheet becomes more equable than in other presses. 

 This press has also the advantage of being much cheap- 

 er than the Stanhope press, and other presses upon a 

 similar construction. 



Clymer's Columbian Press. 



This press, which also depends on a combination Clymer's 

 of levers, was inventeu in Philadelphia in 1814, by Mr. Columbian 

 George Clymer of that city. It was introduced into P rint '"g 

 London in 1818, and a manufactory established for resS g 

 making them. The construction of this press will be 

 readily understood, from an inspection of the elevation 

 in Fig. 6, where A A is the main frame resembling the 

 letter U. The plattin BB, fixed by screws to the bot- 



* An account of the principle of these combinations of levers will be found in the new and enlarged edition of Ferguson's Lectures, vol. ii. 

 p. 264. 



3 



