The loss of power by the best of leather packings is 1 per cent. on 4 in. ram, 1/2 per cent. with 8 in. ram and 1/4 per cent. with 16 in. ram. HYDRAULIC APPARATUS HYDRAULIC APPARATUS. _Apparatus is another name for machinery_ but it also carries the particular meaning of a complete collection of instruments or devices prepared for a particular use, hence, _hydraulic apparatus_ may be said to include very many combinations of machines to utilize the pressure or weight of water. A number of these devices are illustrated in the succeeding pages. It were vain to attempt to describe all. Knight in his Mechanical Dictionary has grouped some six hundred and seventy five terms and names under the heading of “Hydraulic Engineering and Devices.” In the note are given some terms, the definition of which the student may, perhaps, look up; thus: Gyle (the first term given) is a large cistern or vat. The liquor gyle in a brewery is the water-vat or _gyle-tun_. _Hydraulic apparatus has been developed mainly from two sources._ The “cut and try” method, which of course was the first and second from scientific calculations, based upon both the experiments and upon the mathematics of hydraulics. It is difficult at this date to say to which procedure the world is the most indebted, but it is plainly discernable that the two methods have been necessary as a check upon each other. Untold thousands of practical experiments and an almost equal number of tables, rules and calculations have been made. The result has been that out of many failures the point of economy and efficiency, aimed at, of hydraulic apparatus is well defined. NOTE.—_Terms relating to hydraulics named by Edward H. Knight, Civil and Mechanical Engineer, as above._ Gyle; Sluice Valve; The Sough; Stade; Worm-safe; Weel; Water-twist; Water-lute; Water-gilding; Vineficatur; Tun; Tide-lock; Tail-bag; Swash-bank; Sump; Stop-plank; Sterhydraulic apparatus; Staith; Rip-rap; Quay; Puffer; Psychrometer; Levee; Leam; Leach; Land tank; Kiddle; Kimelin; Keir; Jetty; Invert Burette; Hydraulic Blower, etc. Some of these terms go “way back,” and the above are a specimen only of the 675 headings. [Illustration: FIG. 137. SECTION OF CLAW TYPE HYDRAULIC JACK.] HYDRAULIC JACK.