[ 4M ] 
I. A ^Defcription of a Water-Level to be 
fi%d to Daviss Quadrant, whereby an 
Obfervation may be taken at Sea, in thick 
and hazy Weather, without feeing the 
Horizon j by Charles Leigh, Gent. 
H E Sea-Quadrant now in Ufe, called Captain 
‘Davis's Quadrant, being invented by that in- 
genious Gentleman, for taking the Sun's Al- 
titude, is an Inftrument well known, univerfally ap- 
proved, and fufficiently accurate ; I fay fufficiently, 
becaufe it is well known to all Artifts at Sea, that 
five or ten Minutes Error (which is generally the 
mod, if the Inftrument be good, though the Motion 
be great) is a Trifle fcarce worth the noting, either in 
failing near a Meridian, or parallel Circle. This, to- 
gether with a long Ufe of this Inftrument, has, to 
my Knowledge, (having had the Experience of 17 
Years in the Royal Navy) occaftoned Inch a Fondnefs 
to it, that it would be no eafy matter to difluade the 
Navigator from the Ufe of it, to any other. 
It is true, that when the natural Horizon is obfeured 
by thick and hazy Weather, (which is very frequently 
the Cafe, efpecially off of our Chanel, the Banks 
of Newfoundland , 6cc.) this Inftrument, as it now 
{lands, is of no Ufe 3 which too often occafions me- 
lancholy Confequences, filch as the Lofs of Ships and 
Cargoes, and, what is ftill more valuable, our Sea- 
mens Lives. If therefore, to this Inftrument, an 
Apparatus were added, fuch as an artificial or portable 
Nov. 3. 1737. 
Hhh 
Horizon*, 
