PURCHASES.
(1) Single Whip.—A rope rove through a single block fixed in any position. No power is gained (Fig. 92).
(2). Double Whip.—A rope rove through two single blocks—upper block a tail block, lower one a movable hook block. Power gained—double (Fig. 93).
(3). A Runner adds an additional power to the purchase it is used with (Fig. 94).
(4). Gun Tackle.—single blocks. Power gained—twice or thrice, according to which is the movable block (Fig. 95).
(5). Handy Billy or Jigger.—A small tackle for general use; a double block with a tail and single block with hook (Fig. 96).
(6). Watch Tackle or Luff Tackle.—Double hook block and single hook block (Fig. 97).
(7). Double Luff.—Two double blocks (Fig. 98).
(8). Three-Fold Purchase.—Two three-fold blocks. Power gained—six or seven times (Fig. 99).
(9). Four-Fold Purchase.—Two four-fold blocks. Power gained—eight or nine times (Fig. 100).
(10). A Single Spanish Burton.—Two single blocks and a hook. Power gained—three times (Fig. 101).
(11). A Double Spanish Burton.—There are two forms of this purchase—Fig. 102, by using three single blocks; Fig. 103, by using one double block and two single blocks. Power gained—five times.
(12). A Spanish Windlass.—To rig a Spanish Windlass take a good strand well greased in the centre. Place the strand over the two parts of the rope that are to be hove together, and bringing the ends of the strand up again, place a bolt close to the strand. Take the ends of the strand and lay them up with their own parts so as to form two eyes. Take a round turn with this round the bolt, put a marline-spike through each eye and heave around (Fig. 104).
