136 IMPROVED CAPSTAN AND WINDLASS. 



Disadvantages. This violent forcing of the coils upwards along the barrel 

 of the capstan not only adds lonsiderably to the labour in 

 turning the capstan, but from the great friction which the 

 messenger must suffer in the operation, while pressed so hard 

 against the capstan, (as it must be by the weight of the an-^ 

 chor and strain of the men,) could not but cause a very great 

 wear and injury to the messenger, or other cable wound round 

 the capstan ; and that this wear must occasion an expense of 

 no small amount, must be manifest on considering the large 

 sums which the smallest cables used for this purpose cost. 

 Second at- The next method applied to prevent surging was that for 



^' ' , which Mr. Plucknet obtained a patent, the specification of 

 which may be seen in the Repevtoiy of Arts, No. 46. In 

 this way a number of upright puppets or lifters, placed round 

 the capstan, were made to rise in succession, as the capstan 

 tu.nedrourd, by a circular inclined plane placed beneath 

 theui. over which their lower extremities moved on friction 

 whf^els; and tnese puppets, as they rose, forced upwards the 

 coils of the messenger on the barrel of the capstan. 

 This something This was a superior method to the first, as the operation 

 better. ^^ forcing upward the coils was performed more gradually 



by it; but still the wear of the messenger from the lateral 

 friction in rising against the whelps of the capstan remained 

 xind'iminishi-d. 

 Til rd at- 'j'tj^ third method used for the same purpose was that pro- 



posed bj captain Hamilton. It consisted in giving the cap- 

 stan a conical shape, with an angle so obtuse, that the strain 

 of the messenger forced the coils to ascend along the sloped 

 sides of 'he barrel. The roller first mentioned was some- 

 timts used with this capstan, of which a full account is in- 

 serted in the Repertory of Arts, vol. 2. 

 Friction as Tht lateral friction, and wear of the messenger against the 



gic an '. at- ^^^^.ipg ^f the capstan, are ecjually great in this method as in 

 new r oiive- the others ; nnd it, besides, has the inconvenience of causing 

 nieuce. ^^^ ^Q-|g ^^ become loose as they ascend; for as the upper 



part of the barrel is near a third less in diameter than the 

 lovv-er part, the round of the messenger, that tightly embraced 

 the lower part, must exceed the circumference of the upper 

 extremity in the same proportion. 

 Advantages of In the method of preventing the necessity of sitrglng, 

 ' ' ■ which 



