286 NATUftAL &quot;HISTORY 





like a spur or a triangle, with a mast or piece of timber in 

 that corner of the top, that they may contract the wmd 

 more sharply, and cut the outward air more powerfully. 

 And that angle (as we suppose) must not be altogether 

 sharp, but like a short obtuse triangle, that it may have 

 some breadth. Neither do we know what good it would 

 do, if there were as it were a sail made in a sail ; if in the 

 middle of a greater sail there were a kind of a purse, not 

 altogether loose, of canvass, but with ribs of wood, which 

 should take up the wind in the middle of the sail, and 

 bring it into a sharpness. 



10. The third fountain or original of impulsion, is in the 

 place where the wind hits, and that is twofold ; for from 

 the fore side of the ship the impulsion is easier and stronger 

 than on the hinder part ; and from the upper part of the 

 mast and sail than from the lower part. 



11. Neither seems the industry of man to have been ig 

 norant of this, when in a fore-wind their greatest hopes 

 have been in their foremasts, and in calms they have not 

 been careless in hoisting up of their topsails. Neither for 

 the present do we find what may be added to human indus 

 try in this point, unless concerning the first we should set 

 up two or three foremasts (the first upright and the rest 

 sloping) whose sails shall hang downward ; and as for the 

 second, that the foresails should be enlarged at the top, and 

 made less sharp than they usually are: But in both we 

 must take heed of the inconvenience of danger, in sinking 

 the ship too much. 



The Motion of Winds in other Engines of Man s 

 Invention. . 



I. The motion of windmills hath no subtilty at all in it: 

 and yet usually it is not well explained nor demonstrated. 

 The sails are set right and direct opposite against the wind 

 which bloweth. One side of the sail lies to the wind, the 

 other side by little and little bends itself, and gets itself 

 away from the wind. But the turning and continuance of 

 the motion is always caused by the lower part, namely, that 

 which is farthest from the wind. But the wind overcasting 

 itself against the engine is contracted and restrained by 

 the four sails, and is constrained to take its way in four 

 spaces. The wind doth not well endure that compression ; 

 wherefore of necessity it must as it were with its elbow hit 

 the sides of the sails, and so turn them, even as little whirli 

 gigs that children play withal are turned with the fingers. 



