32

NIOHOLLS'S SEAMANSHIP AND NAUTICAL KNOWLEDGE

* Double Purchase.—Two double blocks. Power gained is 4 or 5
depending on which is the moving block (Fig. 91).

Three-Fold Purchase.—Two three-fold blocks. Power gained—
six or seven times (Fig. 92).

Fig. 91.

Fig. 94.

Fig. 95.
Two single blocks and a hook. Power

A Single Spanish Burton.
gained—three times (Fig. 93).
A Double Spanish Burton—There are two forms of this purchase