SAFETY APPARATUS 



729 



N.B. The column in the table on p. 728, marked extract by weight in -100, is Mr. 

 Bate's ; it may be compared -with the preceding short table on p. 727, and also with 

 the table of Malt Infusions in this Dictionary. See BEKR ; MALT ; FERMENTATION. 



If the decimal part of the number denoting the specific gravity of syrup be mul- 

 tiplied by 26, the product -will denote very nearly the quantity of sugar per gallon in 

 pounds at the given specific gravity. 



SACK. A general name for a large bag. Its capacity varies much ; it may 

 therefore be useful to give a few examples of its capacity in different places : 



Winchester 



bnshels 



the minimum French sack is . . . 2'012 

 maximum ditto .... 4 - 256 



the sack is 6'90. 



the miller's sack is . . . . 2*00. 

 ordinary sack of salt . . . . 215 Ibs. 



j" 2 weys. 



the sack of wool \ 13 tods. 



I 364 Ibs. 



sack of flour or corn .... 280 Ibs., or 2 cwts. 2 qrs. 

 sack of coals formerly .... 3 bushels. 

 do. recent .... 2 cwts. 



France : 



Brussels . 

 America : 



England , 



{3 heaped bushels. 

 < 



sack of dry goods \4strikebushels. 



Sack is also a loose robe. A name formerly given to sherry. 

 SACXCIiOTH. A coarse baling or wrapping. 



SACKING. A coarse kind of hemp fabric, made chiefly in Dundee and in the 

 north of Ireland. 

 SAFETY APPARATUS, for the prevention of over-winding in mines. Numo- 



1734 



rous arrangements many of them very in- 

 genious have been introduced from time to 

 time, to prevent the accidents which have 

 very often arisen from winding the cage, con- 

 taining men, over the pulley, or the load, 

 which, breaking away, falls of course to the 

 bottom of the shaft. 



Two of the latest inventions for this pur- 

 pose are all that can be admitted with the 

 space at disposal. The first of these is 

 Walker's Detaching Hook, and the second 

 King's Safety Apparatus. 



The principle in each invention is the same, 

 and the safety in either case is obtained from, 

 the fact, that if the load is raised above a 

 certain point, the weight of the load compels 

 the rope to become detached, which detaching 

 cannot take place until the 'jaw hooks ' have 

 a firm hold on the supporting ring. 



Fig. 1734 is the front view of Walker's 

 detaching hook, with the supporting ring and 

 clamp in section, and fig. 1735 is another 

 view of the same after the hook is de- 

 tached. 



The lifting rope is attached to the shackle 

 A, and the load to the connecting link B. 



The supporting ring, c (through which the 

 rope is constantly working), is a fixture in a 

 baulk of timber, or iron girder, at the pit top. 



The hook consists of a pair of jaws, D, D, 

 working on a centre-pin, u, in such a manner 

 that the weight of the load has a tendency to 

 open the upper limbs, which clip the strong 

 centre-pin of the shackle A. The upper limbs 

 are formed externally with jaw hooks, F, F. 

 The jaws are kept together, and made to re- 

 tain the shackle-pin by means of the clamp 

 H, which is held in position by the pins r, i. 



In case of overwinding, the jaw hooks (held together by the clamp) pass freely into 



