j6 2 Gen. Hoy’s Account of 
ment to a greater height than fifteen or fixteen feet above the 
ground. The whole together was never made ufe of, except 
at the two extremities of the Hounfiow Heath bafe. The 
uppermoft half was applied at three of the ftations only, 
namely, St. Ann’s Hill, Botley Bill, and Padlefworth near 
Dover. 
Art. II. tripod Ladder . 
Next to the feaffoid the plate reprefents, in plan and feftion, 
a tripod ladder, about thirty-five feet in height. It carries on 
its top a globe lamp, of about one foot in diameter, in which 
was ufed a fimple Argand’s burner, of a large fize, made for 
that purpofe. The lamp being removed, a focket for a white 
light might occafionally be fubftituted in its place; or (as was 
the cafe when we obferved the ftation at King’s Arbour from 
St. Ann’s Bill) a flag-ftaff might be added at the top, which 
was fecured in a truly vertical pofition, by braces fixed to the legs 
of the ladder underneath. It will be readily conceived, that by 
a contrivance of this fort a white light could be raifed to a con- 
fiderable height above the ground, if the circumftances at any 
time had rendered fuch elevation neceffary ; and that it could, by 
the help of a heavy plummet, be always placed in a truly 
vertical pofition over the point on the ground marking the fta- 
tion. The globe lamp was found to anfwer very well for fhort 
diftances of fix or eight miles, when the weather was favoura- 
ble; but it could not be depended upon in obfervations of 
diftances that were confiderably greater. 
Art. III. Common Flag faff. 
After the tripod ladder, comes in the plate the plan and 
elevation of a common flag-ftaff with its braces, carrying 
? likewife 
