•i— into 
r 
I ^t^,6ca 
5040 
In this the firft two fleps ar€ generally fufficknt for Nau- 
tical ufes, efpecially when neither of the Latitudes exceed 
60 degrees, and the difference of Latitudes doth not pafi- 
30 degrees. 
But I am fenfible I have already faid too much for the 
Learned, tho' too little for the Learner ; to liich lean re- 
commend no better Treatife, than that of Dr. WaHis in 
Numb. 176. wherein he has with his ufual brevity, and that 
perlpecuity peculiar to h^mfelf, handled this Subje(a: from 
the firft Principles, which here for the mbft part we (up- 
pofe known. 
I need not fiiew how, by regreffive work, to find the La- 
titudes from the Meridional Parts, thg? Method being fuffi- 
ciently obvious. I fhall only conclude with the propofal of 
a Problem which remains to make this Doi^rine complect, 
and that is this. ' | 
A fliip (ails from a given Latitude, and having run a cer- 
[ tain number of Leagues, has alteied her Longitude by a gi- 
ven angle. It is required, to find the Gour^ fiie Iteared. 
I ^ The folution hereof would be very accej)table, if |iot to the 
, publick, at leaft to the Author of diisTxad, being'likely to 
open Tome further Light into the Myiieries of Geometry.' 
To Conclude/ 1 ftiall only add, that Unity being Radius, 
the Co(ine of the Arch according to the fame Rules of 
Mr. Newton, will be * 
from which and the former Smes exliibiang the Sine by the 
Arch, by divifion it is eafie to- conclude, chat the Natural 
Tangent to the Arch ^ is 
K k A 
