MECHANICS AND USEFUL ARTS. 87 



feeding. Above it and a few inches back of the front edge of the top sheet, 

 a number of small vertical cylinders stand in a row parallel to the printing 

 cylinder. Each of these cylinders is a small engine, closed at top and open 

 at the bottom, inside of which is a piston, provided with a piston-rod suffi- 

 ciently long to reach the paper when the piston is down. All the rods are 

 articulated, an elongated hole is cut in each for a crank-pin to pass through, 

 and by means of a cranked shaft they are made to move constantly back- 

 ward and forward. The ends of the piston-rods are so arranged as to slide 

 on the paper when moving backward, and as to carry it forward during the 

 forward stroke. Each piston is pressed down by a coiled spring placed in 

 the cylinder between the piston and the top cover. From each cylinder a 

 pipe extends to the edge of the feeding-board nearest the roller, where it is 

 flattened, and its lower portion resting on the feeding-board, is pierced with 

 a small hole. All the cylinders are also connected with an exhaust air-pump, 

 constantly at work. The machinery operates as follows: The piston-rods 

 working backward and forward in contact with the top sheet, brings it for- 

 ward to the edge of the feeding-board. The moment it arrives there, the 

 suction of the exhaust pump makes the sheet close hermetically the small 

 holes in the pipes. A vacuum in the cylinders, and the rising of the piston 

 against the coil springs, are the immediate results of this closing. The 

 piston-rods recede from the paper, which is left at rest, till the iron fingers 

 of the roller seize it and carry it to the form. The moment the sheet is car- 

 ried off, the holes in the pipes are left open, air rushes through them into tho 

 cylinders, fills the vacuum, the pistons are pushed down by the coil springs, 

 and the ends of the piston-rods carry the next sheet forward. Several of the 

 cylinders work at right angles with the first, to insure a proper register side- 

 wise. There are also a few incidental arrangements, such as the raising of 

 all the pipes from the paper at the moment the last is clenched. There are 

 several good patented plans for making a mechanical feeder for separate 

 sheets, but none better than the one described. The nature of the work re- 

 quires an attendant, and as feeding does not require a long apprenticeship, 

 there is little difference between the wages of a feeder and those of a boy. 

 The advantage of the apparatus seems then to consist in the possibility of 

 running presses faster. Book printers cannot avail themselves of it, as, for 

 the purpose of making neater copies, the presses are actually run slower than 

 they could be fed by hand. The apparatus would be advantageous for news- 

 paper rotary presses, in which rapidity is everything; but in this case feed- 

 ing with endless paper is still a better plan, which, sooner or later, will 

 supersede all others. New York Tribune. 



CLAY RETORTS FOR GAS-MAKING. 



A paper has been read to the Institution of Civil Engineers, London, " On 

 the Results of the Use of Clay Retorts for Gas-making," by Mr. Jabez 

 Church. The substitution of fire-clay for metal, in the construction of 

 retorts, was attributed to Mr. Grafton, and dated back as far as the year 1820. 

 Originally they were square in transverse section ; but that form was soon 

 changed for the Q, or oven-shape, which had been since adhered to, both in 

 this country and abroad; this latter form of retort admitting of a stratum of 

 coal being distributed of an equal thickness throughout. 



The comparative quantities of gas made by iron and clay retorts, of the Q 



