86 ANNUAL OF SCIENTIFIC DISCOVERY. 



would sink the largest ship (even the Leviathan) or floating battery. 



as no precaution could save either garrison or town from such shells, so their 



moral effect would be paralyzing. 



A single 36-inch shell in flight costs 25, and a single 13-inch 2 2s., 

 yet the former is immeasurably the cheaper projectile; for to transfer to the 

 point of effect the same weight of bursting powder we must give 



55 shells of 13 inches, at 2 2s., - .115 10 



Against 1 shell of 36 inches, - 25 



Showing a saving in favor of the large shell of .90 10 



and this assumes that fifty -five small shells, or any number of them, could 

 do the work of the single great one. 



The mortars are, with the exception of one part (the base), and the elm 

 timber ends, formed wholly of wrought iron, in concentric rings, and each 

 entire mortar is separable at pleasure into thirteen separate pieces, the 

 heaviest of which weighs about eleven tons ; so that the immense weight, 

 when all put together (about fifty-two tons), is susceptible of easy transport, 

 on ordinary artillery carriages, over rough country, or can be conveniently 

 shipped, stowed, or landed. 



NEW METHOD OF PRINTING. 



A description of a new method of printing, invented by a journeyman 

 printer, and called by him NeograpJiy, has recently been published in Paris. 

 The object sought to be attained is to obtain printing surfaces of a better 

 quality than stone, zinc, or any other substance hitherto used; and, more- 

 over, to get impressions of different colors by a single operation, instead of 

 bringing the sheet under the press several times. The modus operandi is as 

 follows : The figures or characters to be produced are drawn upon a woven 

 stuff, or any other which may be penetrated by a liquid ; the ink used for the 

 purpose is composed of lampblack, Indian ink, gum, sugar, and common 

 salt. This done, the side on which the figures have been drawn receives a 

 slight coating of gutta-percha, and when this is dry the surface is washed. 

 Now, since the ink is composed of soluble matter, this will wash off, and the 

 gutta-percha which covered the characters, and which therefore does not ad- 

 here to the stuff, washes off too, by which means the stuff becomes a surface 

 which is only penetrable by liquids in those places where the characters were 

 drawn, and is perfectly impenetrable everywhere else. This done, the wrong 

 side of the stuff receives the inks and colors which are to serve for printing, 

 while the sheet is laid on the right side. Under the action of the press, the 

 ink and colors penetrate through the unprotected places, and a clear impres- 

 sion is obtained. Instead of applying the ink and colors as stated, a perma- 

 nent kind of cushion, made much like the balls formerly used for inking 

 type, and properly charged with ink or colors, may be placed under the 

 stuff, and thus many sheets may be worked off before it is necessary to 

 renew the ink. 



BULLOCK'S MECHANICAL FEEDER FOR PRINTING PRESSES. 



This machine, now in successful use in New York, operates as follows : A 

 pile of sheets is placed upon the feeding-board in the manner usual for hand- 



