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POPULAR SCIENCE REVIEW. 
each three feet in diameter, at a rate of 300 revolutions per 
minute. 
A tent was erected on the Downs two miles from Chard, and 
for seven weeks the two experimenters continued their labours 
— not, however, without much annoyance from intruders. In 
the language of Mr. Stringfellow, “There stood our aerial 
protegee in all her purity — too delicate, too fragile, too beautiful 
for this rough world ; at least, those were my ideas at the time, 
but little did I think how soon it was to be realised. I soon 
found, before I had time to introduce the spark, a drooping in 
the wings, a flagging in all the parts. In less than ten minutes 
the machine was saturated with wet from a deposit of dew, so 
that anything like a trial was impossible by night. I did not 
consider we could get the silk tight and rigid enough. Indeed, 
the framework altogether was too weak. The steam engine was 
the best part. Our want of success was not for want of power 
or sustaining surface, but for want of proper adaptation of the 
means to the end of the various parts.” 
Many trials by day down inclined wide rails showed a faulty 
construction, and its lightness proved an obstacle to its success- 
fully contending with the ground currents. 
Shortly after this, ^Ir. Henson left England for America, 
and Mr. Stringfellow, far from discouraged, renewed alone his 
experiments. In 1846 he commenced a smaller model for in- 
door trial, and, although very imperfect, it was the most sue-* 
cessful of his attempts. 
The accompanying illustration (Plate XXXVI. fig. 1) is taken 
from a photograph. It will be observed that the sustaining 
planes were much like the wings of a bird. They were ten 
feet from tip to tip, feathered at the back edge, and curved 
a little on the under side. The plane was two feet across at 
its widest part ; sustaining surface, seventeen square feet ; and 
the propellers were sixteen inches in diameter, with four blades 
occupying three-fourths of the area of circumference, set at an 
angle of sixty degrees. The cylinder of the steam engine was 
three-fourths of an inch in diameter ; length of stroke, two 
inches ; bevel gear on crank shaft, giving three revolutions of 
the propellers to one stroke of the engine. The weight of the 
entire incKlel and engine was six pounds, and with water and 
fuel, it did not exceed six and a half pounds. 
The room wliich he had available for experiments did not 
mca‘>ure above twenty-two yards in length, and was rather con- 
tnicted in height, so that he was obliged to keep his starting 
wires very low. He found, Imwever, upon setting his engine in 
motion, that in one-third the length of its run upon the ex- 
tended wire, the machine w’as enabled to sustain itself; and 
up^ui its reaching the point of self-detachment, it gradually 
