100 ANNUAL OF SCIENTIFIC DISCOVERT. 



uniformly even and invariably successful. 6. There is no longer any danger 

 of distorting nor of lengthening, by rolling out the plates in copper-plate 

 printing, nor of breaking the lithographic stones by the uneven pressure of 

 the-scraper. 7. The simplicity of the contrivance for locking the press, and 

 for admitting and shutting off the pressure, renders all mistakes impossible. 

 8. There is no part of the press which is expensive from excessive wear and 

 tear; and even when worn out, both the caoutchouc and the metal have a 

 considerable value as raw material. 



As an investment, the great simplicity of the machinery, and the small 

 expense of fitting, will allow the press to be sold extremely cheap. 



As to the sort of pressure to be used, steam pressure may be adopted, or 

 the pressure of expanded or condensed air, the hydraulic press, the screw, 

 the cam, or the eccentric or knee lever lock. If steam is used, the waste 

 heat will warm the plates in copper-plate printing, and will thus get rid of 

 the charcoal dust, so injurious to the health of the workmen. 



The expenditure of water or steam may be estimated by considering the 

 surface of the caoutchouc as the surface of a piston, and its depression 

 joined to that of the printed surface as the stroke of the piston; conse- 

 quently, when the basin is one metre square, there is an expenditure of one 

 litre of ah' or water for each millimetre in the depression of the surface. 



Water appears, on the whole, the most desirable agent, on account of its 

 non-compressibility, and of the small quantity required in order to pi-odnce 

 very considerable pressure, as also on account of its non-expansibility, 

 which prevents the possibility of an explosion; for if any breakage takes 

 place, the water simply runs out. In experiments which were made with a 

 pressure of from twenty to thirty atmospheres, before perfecting the press, 

 the vessel repeatedly burst, with no greater injury to those engaged than a 

 few splashes on their clothes. 



TYPE 3IAP. 



A telegraphic map of Europe, entirely executed in typography, has been 

 issued by the Royal Printing Office of Berlin. The process by which it has 

 been produced is described as follows: The drawing of the map, made on 

 paper, is blackened at the back with a carbon tracing composition, and is 

 placed, blackened side downwards, on a surface composed of quadrats, 

 formed each by sixteen nonpareil squares, and by means of a point, the lines 

 are transferred to them. The quadrats over which these lines are traced are 

 then exchanged for nonpareil type, cast with a face of points, and the coast 

 line is formed by the inner portion of these points being cut away. The 

 telegraphic lines are formed of brass rules, fixed in nonpareil type body, as 

 a sort of legs, which can be inserted into the composition, when needed, by 

 taking out the quadrat the legs being so adjusted in length that the upper 

 edge of the rule is level with the face of the type. The additional shading 

 of the coast line is effected by the insertion of nonpareil type cast with points 

 on the face. The names of places are inserted by means of type talcing the 

 place of the quadrats where required. 



The effect produced is peculiarly good. How far this is ever likely to su- 

 persede the present methods of producing maps by engraving and transfer 

 to lithographic stone, is questionable; no details as to the cost are given, 

 and it seems very doubtful (however simple the process appears) whether 

 the result can be satisfactorily produced except by a skilled workman, whose 

 labor must be adequately remunerated. 



