.MECHANICS AND USEFUL ARTS. 31 



* 



highly recommend, have been put in use. The largest are worked 

 by driving-pipes 6 inches in diameter. One of this size, with a fall 

 of 6 feet, lifts 20,000 gallons per day 60 .feet. The improvements 

 described permit the instruments to be made of much larger size than 

 usual, and they last longer and are less liable to get out of order. 



HYDRAULIC PRESSURE IN COAL-MINES. 



IT is stated that a powerful hydraulic engine is used at the Minton 

 Colliery, for the purpose of drawing the trains of wagons under 

 ground, without the aid of steam-engine or of horses. The engine 

 consists of two small cylinders and pistons, each being 3 inches in 

 diameter, with a 12-inch stroke ; the water which supplies the power 

 is that pumped from the shaft, collected in a reservoir 606 feet above 

 the level of the water-engine, and, of course, applying an enormous 

 force on the pistons ; the pipes conveying the water down the shaft 

 are 4k inches in diameter ; the distance from the shaft, whence the 

 trains are at present propelled, is 880 yards, with gradients from 

 1 in 30 to 1 in 18 ; the number of tubs in each train is 20 ; the speed 

 is at the rate of 6 miles per hour ; the quantity of water pressing on 

 the pistons is 1,500 gallons, and the average speed 100 strokes per 

 minute ; the power of the engine is about 30 horses, and the reservoir 

 and column of water collects enough to draw 20 trains a day ; but al- 

 though it is contemplated to increase that number to 50, that extra 

 number will only involve the pumping of an extra 30 gallons per 

 minute through the 24 hours. Cii-il Engineer and Architect's Journal, 

 May. 



CYLINDRICAL ROTARY PRINTING-PRESS. 



% 



THE New York Tribune describes a new printing-press, the invention 

 of Mr. J. A. Wilkinson, of Providence, R. I. It says, "All the mo- 

 tions of this press are rotary. The types are adapted to and brought 

 into a perfectly circular form, and placed on cylinders, one of which 

 is made to print the upper, and the other the under side of a continuous 

 sheet of paper, which is made to pass directly through the machine 

 and come out printed on both sides, folded into a convenient form, and 

 cut off ready for delivery. All the reciprocating movements here- 

 tofore used are abandoned, and simple rotary motions substituted 

 throughout. Consequently, the exceedingly smooth and uniform ac- 

 tion of this press is almost exempt from the danger of getting out of 

 order, and subject to very little wear. The types, moreover, possess, 

 in their shape, a great advantage. They are so formed that they 

 must necessarily all stand the right way, and in their action upon the 

 paper are not subject to injury by being battered ; and they are much 

 less worn and disfigured by use than type employed in the old way. 

 To which may also be added the important advantage of casting upon 

 the radii of a circle, and using upon the cylinder stereotype plates 

 exactly conformable to the cylinder, and made to move, like the type, 

 completely in a circle. The velocity in the movement of this press is 



