90 



APPENDIX. 



1. The efFedls of currents. 



2. The yawing of the fliip going with the wind aft, 

 or upon the quarter, when fhe is feldom fleered within a 

 point each way : this I mention as an error in the diftance, 

 and not in the courfe ; fince, though the (hip by being 

 yawed equally each way may make the intended courfe 

 good upon the whole, yet the diftance will be fhortened 

 as the verfed fine of the angle between the line intended 

 and that fteered upon. 



3. By the (hip being driven on by the fwell, or the log 

 during the time of heaving being thrown up nearer the 

 fhip. 



4. By the log coming home, or being drawn after the 

 {hip, by the fridtion of the reel and the lightnefs of the 

 log. Norwood mentions thefe two laft, and fays, " For 

 " thefe caufes, it is like, there may fometimes be allowed 

 ** three or four fathoms more than is veered out; but this, 

 " (as a thing mutable and uncertain) being fometimes 

 " more, fometimes lefs, cannot be brought to any certain 

 " rule, but fuch allowance may be made as a man in his 

 " experience and difcretion finds fit." 



5. By the log being only a mean taken every hour, 

 and confequently liable to error from the variations in the 

 force of the wind during the intervals, for which an arbi- 

 trary corredlion is made by the officer of the watch ; and 

 though men of fkill and experience come near the truth, 

 yet this allowance muft, from its nature, be inaccu- 

 rate. 



4 Thefe 



