48 ON A FORM OF FLYING-MACHINE, — 
These quantities are measured from fig V with a bastard scale, 
30 units of which are equal to AB; their sum multiplied by the 
length of cord overhauled at each flap, viz. lfoot, gives 168°8 ft. Ibs. 
as the amount of work done during the flight by the bands. 
e cord is wound ona flat winder 6 inches long; the crank 
shaft is at the centre of the winder, and the cranks are on either 
the top or bottom centre when the winder points t6 the last sheave 
over which the cord passes, that is, they are not quite at right 
angles to the winder. The strain on the crank pins due to the 
flat winder, varies as the cosine of the angle the winder makes with | 
the line joining the centre of the crank-shaft and the last sheave 
The upper end of each connecting rod is fastened to the midrib at 
1°61 in. from the socket, and each wing moves throughan arcof 121° 
The centre of effort of each wing is 25-5 inches from the socket, 
and the length of the arc traversed by it is 53‘8 inches, which is 
taken as the height of the equivalent trochoidal wave. 
e midrib is 5 inches from the forward edge of the wing, which — 
is 9 inches wide, and the.preponderance of the after part of the 
wing membrane twists the midrib about 15°; this shortens the 
equivalent trochoidal wave to 2208 feet, and makes the pitch 
angle 574°. 
The distance the machine flew was 98 feet from where I stood, 
it took a wide sweep of at least 30 feet versed sine, making 120 ft. 
on the curve ; it was stopped by a fence on the top of which it 
caught, 8 feet below the starting-point ; the trajectory was slightly 
ascending at first, but very little. 
e wings are flapped ten times in 7 seconds, which gives a 
horizontal speed of 14°6 miles per hour, or 15 feet per stroke. 
Using the formula P=0-002288 V? where P=-177 Ibs. per 
same time it is translated 120 feet horizontally and 8 feet down- 
wards, so that by the parallelogram of forces the india-rubber bands 
_ drive the machine upwards at an angle of 19° for a distance of 
126°5 feet ; this gives 15-8 feet per stroke, and a slip of 28-4 per 
cent. which represents the skin resistance, 
The strain on each crank-pin at the centre of the first stroke is 
32°15 Ibs., or-2-02 Ibs. on each wing’s centre of effort ; this strain 
ecreases to 0 when the crank is on the centre and. the winder 
pointing towards the last sheave. The angle of the wing with the 
direction of the thrust, and the torsion of the midrib, decrease with 
