[ 3a) 4 
LXIV. On Aérial Navigation. By Sir GrorceCay.ey, Bart. 
F.R.S., &e. 
To Mr. Tilloch. 
Sir, — i aM glad tosee the subject of aérial navigation noticed 
by Mr. Lovel Edgeworth, and likewise by a gentleman under the 
signature of T. H. in your Magazine for March last. Mr. 
William Bland has likewise written an ingenious paper upon this 
subject in the Monthly Magazine for March. I wish to bring 
all those who interest themselves in this invention, to act in 
concert towards its completion, rather than to be jealous of each 
other respecting their own share of credit as inventors : indeed, 
unless we ean realize our object, very little credit will be due to 
these speculations. Mr. Edgeworth, who upon good grounds 
puts in so early a claim to a knowledge of the principle of 
steering balloons by the inclined plane, has quite misconceived 
the nature of the principle upon which my former papers upon 
the subject of aérial navigation were founded, when he says that 
*¢ Sir George Cayley has frequently proposed to impel flying 
bodies by letting them descend obliquely through the air, and 
forcing them in a contrary obliquity against the air by zmpelling 
them upwards.” My plan rested upon the following fact: that 
if a plane of any given magnitude, say 100 square feet, were 
placed so as to make any small angle with an horizontal line, 
suppose an inclination of one to ten; then, if it were propelled 
forward in the horizontal path, like a bird in the act of skim- 
ming, by a force of ten pounds, till the horizontal resistance of the 
air equalied this pressure, the plane would have power to sustain 
one hundred pounds weight during its progress. I proposed to 
create this slight horizontal pressure by the power of a light 
first mover, several of which were there alluded to, particularly 
one where the combustion of oil of tar was made use of as the 
moving power. This engine had been exhibited in a working state 
to Mr. Rennie, Mr. Cartwright, and other gentlemen capable of 
appreciating its powers; and it appeared from the minutes of 
Mr. Chapman, civil engineer of Newcastle, that eighty drops 
raised eight hundred weight the height of twenty-two inches ; 
hence a horse power may consume from ten to twelve pounds 
per hour. The expense of power, however, with this engine 
being much greater than with the steam-engine, the patentee 
never proceeded further than the original experiments. From this 
statement it is plain that the tacking operation alluded to by 
Mr. Edgeworth, —by “impelling them upwards,” and then 
letting gravity operate in the descent,—was not any part of my 
plan, although, being acquainted with the principle of oblique 
Vol. 47, No. 217, May 1816. X forces, 
