1 56 
On the Velocity of the Wind. 
[Ma? 
this screw, we would propose that of Archimedes, one of the oldest mechanical 
contrivances extant, and one which, we should think, might be used with effect, in 
many situations in this country. A correspondent has sent us an account of an 
improvement which has been added in France to this ingenious contrivance. It 
consists m making the screw double, the one being much shorter, but of a huger 
diameter than the other, and set on in a reverse direction. A fall of water of a few 
teet, it sufficiently copious, being admitted to the larger but shorter screw, will, 
by passing through it, turn the machine, and raise a certain quantity through the 
longer sci ew. The proportion is stated to be as high as 6*0 per cent. We shall 
give this paper at length m our next. 
VI. — On the V ?locity of the TVind, 
To the Editor of Gleanings in Science. 
Sir, 
Having accidentally, while on a visit to this port, cast my eye upon an 
article m your last year’s collection of Gleanings, on the subject of the Velocity 
I- feIt rekindled in my bosom all the ardour of experimenting, 
which the dul routine of a maritime life, unsupported by sympathy oi- encourage- 
ment, had well nigh extinguished. It used to be my favorite pastLe, dudn Ahe 
many spare hours of a noisy life, to store up all the information I could obtain 
fiom practice and experiment on the subject of navigation and the construction 
a S compared 1 ME t £& 
rralattonJoMh; IcI of d ° Ubt rdati '' e,y Speakin K> as S ood as 
Being anxious to contribute my share of labour in uprearing the vast fabric of 
expenmentui science, 1 shall hasten to procure an anemSmeSfand to m/ke^od 
useof it in my next voyage ; but, in the mean time, I beg to present you with an 
itAVA t - r ° m my f ° rmei pr,vate lo £> thinking that, with the aid of Smeaton’s table, 
? e enquh ! es of V01ir corresponded Q ’ 
myself may be able to glean from the wide field of nature's grande™ element 
W R N 
wiirtco?r g 7o * * 
anemometer prevents n,e malting any more acc«raL P distin«L s WaDt ° f “ 
Velocity. 
1.47 ft. 
2.03 
4.40 
5.87 
7.33 
11.00 
16.67 
22.00 
29.34 
36.67 
44.01 
51.34 
58.68 
66.01 
73.55 
88.02 
Force on a 
square foot. 
.005 
.020 
.044 
.079 
.123 
.246 
.492 
1.107 
1.968 
3.075 
4.429 
6.C27 
7.873 
9.963 
12.300 
17.715 
Classification according to 
Sineaton. 
Hardly perceptible. 
( Light i 
1 
airs. 
Fine breeze. 
; Brisk gale. . 
■ Fresh gale. . 
; Strong gale. 
Hard gale. . 
Storm... .. 
Classification used by me. 
Light airs. 
5 Light breeze, No. 1. 
(Ditto ditto. No. 2. 
$ Moderate breeze, No. 1. 
I Ditto ditto. No. 2. 
Fresh breeze. 
5 Strong breeze, No. 1. 
I Ditto ditto. No. 2. 
> Gale, No. 1. 
I Fresh gale, No. 2. 
4 Strong gale, No. 1. 
( Ditto ditto. No. 2. 
C Heavy gale. No. 1. 
i Ditto ditto. No. 2. 
C Storm, No. 1. 
t Ditto, No. 2. 
