Description of a Capstaii. 571 



the society represents, none of the lateral friction of the 

 messenger or cable against the whelps of the capstan, 

 (which all the other methods of effecting the same purpose 

 before mentioned labour under,) can possibly take place, 

 and of course the wear of the messenger occasioned thereby 

 will be entirely avoided in it, while it performs its purpose 

 more smoothiy, equally, and with a less moving power than 

 any of them. 



My method of preventing the necessity of surging, con- 

 sists in the simple addition of a second smaller barrel or 

 capstan of less dimensions to the large one; beside which 

 it is to be placed in a similar manner, and which need nol 

 in general exceed the size of a half-barrel cask. The coils 

 of the messenger are to be passed alternately round the la ge 

 capstan and this small barrel, but with their direction re- 

 versed on the different barrels, so that they may, cross each 

 other in the interval between the barrels, in order that they 

 may have the more extensive contact with, and better gr:])e 

 on each barrel. To keep the coils distinct, and prevent their 

 touching each other in passing from one barrel to the other, 

 projecting rings are fastened round each barrel, at a distance 

 from each other equal to about two diameters of the mes- 

 senger and the thickness of the ring. Those rings should 

 be so fixed on the two barrels, that those on one barrel 

 should be exactly opposite the middle of the intervals be- 

 tween those on the other barrel -. and this is the only cir- 

 cumstance which requires any particular attention in the 

 construction of this capstan. The rings should project about 

 as much as the cable or messenger from the barrels, \\ hich 

 may be formed with whelps, and in every other respect, 

 not before mentioned, in the usual manner for capstan bar- 

 rels, only that I wouW recoinmend the whelps to be formed 

 without any inclination inwards at the t<»p, but to stand 

 upright all round, so as to form the bodv of the capstan id 

 the shape of a polygonal prism, if the intervals between the 

 whelps are filled up, in order that the coils miy luive equal 

 tension at the lop and at the bottom of the barrels, and 

 that the defect which conical barrels cause in this respect 

 may be avoided. 



Tlie 



