ENGINEERING. 



307 



frame, bolted to masonry. The piston pulls 

 the beam toward it when it descends, and 

 carries along in the same motion the shear?, 

 as well as the load suspended from their point 

 of junction, and the load is thus carried to a 

 distance of 16 feet from the edge of the wharf 

 in order to be placed upon a car. Conversely, 

 if the piston rises, it pushes before it the entire 

 framework, as well as the lifting apparatus, so 

 that the latter can be lowered on a line 28 feet 

 beyond the face of the wharf. 



The lifting apparatus consists likewise of a 

 hydraulic press suspended from the summit of 

 the tripod ; but, in order to prevent the joints 

 of the cylinder from working under the action 

 of the load, which would tend to open them 

 and cause leakages, it is not suspended from 

 the exact axis of the junction of the shears. 

 The cylinder rests directly upon a huge stirrup 

 45 feet in length, the arms alone of which are 

 affixed to the axis, through a Cardan joint. 

 Under such circumstances, the stress of the 

 load carried by the piston-rod is exerted solely 

 upon the branches of the stirrup, and the sides 

 of the cylinder work only under the pressure 

 of the motive water. The latter is introduced 



FIG. 9. AUTOMATIC MULTIPLIER (WITH SHEARS). 



at the base of the press, through a valve oper- 

 ated at will by a man who stands upon a plat- 

 form arranged for the purpose. 



In order to produce the three powers of 25, 

 75. and 120 tons called for by the specifica- 

 tions, and at the same time expend in each 

 case a corresponding quantity of water under 

 pressure, it is of course necessary to cause the 

 re of the motive water to vary in pro- 

 portion. This result is reached by calculating 

 the diameter of the two cylinders so as to ob- 

 tain the mean power of 75 tons, in making the 

 water of the general conduit act directly under 



the normal pressure of 50 atmospheres. Fur 

 the powers of 25 and 120 tons, use is made of 

 an automatic multiplier, which consists of two 

 cylinders arranged end to end, in which move 

 pistons A and B (Fig. 9) of different diame- 

 ters. When it is a question of lifting 120 tons, 

 the water at 50 atmospheres actuates the pis- 

 ton A, and B forces water into the lifting cylin- 

 der under a largely incre.-ised pressure. If the 

 load to be lifted is but 25 tons, the water at 50 

 atmospheres actuates the piston B, and A 

 forces the water into the same cylinder at a 

 much lower pressure. The same operations 

 are effected in the other cylinder when the 

 extreme loads of 25 and 120 tons are moved. 

 The shears are likewise provided with a hy- 

 draulic cylinder (Fig. 8), placed on the back 

 of the beam, and serving through a cable, 

 to bring the piston of the large cylinder to tl.e 

 end of its upward stroke, and for certain ac- 

 cessory work. Finally, the apparatus as a 

 whole is completed by an accumulator con- 

 taining in reserve a large part of the water 

 necessary for each operation. 



Steamships, A noteworthy step in the devel- 

 opment of *team navigation is found in the 

 sister-ships, the "City of Xew York" and the 

 "City of Paris." The first of these was in 

 active service during the summer, and the last 

 was nearly ready for her trial trip at the end of 

 the year. Not only are these vessels larger 

 than any other of the Atlantic liners, but the 

 twin-screw principle receives in them its fir-t 

 trial on a large scale for the merchant service. 



The builders are Messrs. James and George 

 Thompson, of Clydebank, near Glasgow, who 

 have turned out many of the fin 

 afloat. The particulars of the design were left 

 to them, the only conditions specified by the 

 Inman Company being that the vessels were to 

 be unsinkable. as comfortable as any hotel, and 

 as swift as possible consistently with the con- 

 ditions first named. The following table shows 

 at once the dimensions of these latest additions 

 to the fleet, and the development of first-class 

 passenger steamers since the earliest days of 

 regular transatlantic steam navigation : 



TABLE GIVING CHIEF DIMENSIONS OF NOTABLE ATLANTIC LINERS. 



NOTE. Those marked * were built of wood, t of iron, and J of steel. 



