NOTE. 
HAD not yet recovered from long-continued illnefs at the time the 
following letter was written, and could therefore give no perfonal 
attention to the experiments alluded to. The letter relates to the 
fanning-wheel I have fpoken of. The writer, Mr. A. P. Brown, of 
New York City, U.S.A., an ingenious mechanic, was employed by me to con- 
ftrudf and experiment with the wheel: and among other things, I had directed 
him to obferve the lifting effedt of the wind-blaft upon a canopy or fail: this is 
what he alludes to in one part of his letter. I quote the letter, as it may pof- 
fibly intereft some of thofe whofe attention, like my own, has been directed to 
this subject:— 
“ New York, January 20th, 1882. 
“Friend H-, 
* * * * “ The wheel is of 3 fans—each 9^- inches by nearly 3 inches in 
the wideft part. It is pulled by a cord wound on a crank-wheel, and gets 80 
turns at once winding up. It got 90 with the smalleft cord here enclofed ” 
(about like fhoemaker’s thread), “ but the cord broke. To get 80 turns of 
the ‘fly,’ 12 turns of the crank-wheel are required. Time confumed is 10 
feconds. So the velocity of the fly is 480 per minute.’’ (This don’t amount to 
much in comparifon with the 18,000 of the real “ fly! ”) “ At and during 9 to 
1 o of the firfl: turns the air draws towards the wheel from front and rear alfo. 
This means that the wheel rarefies the air in its immediate neighbourhood, pair¬ 
ing it off radially to itfelf. ” (The little miller did far better than this.) “ By 
the end of this time fufficient velocity is attained to Jet the fails afkew t and a 
backward current gets itfelf eftablifhed , and continues with reafonable and in- 
creafing uniformity to the clofe of the experiment.” (This fettles the queftion of 
Rotary wings, and proves my theory of automatic adjujlment of the wing-fans by 
air-preflure; and equally proves the applicability of the wheel, when conftrudted 
with properly organized preffure-blades , to water as a propeller in lieu of the 
wafteful and imperfedt “ fcrew ” now in use.) 
“ The wheel only makes 1 to 2 revolutions at the utmoft, after the cord is 
all wound off. There is a tendency in the air-current to Ihifit it from fide to fide 
a little; perhaps the operator’s arm or Ihoulder or head may caufe it. There is 
alfo a noticeable fide inclination to the current next to the wheel from left to 
