~ 
336 Proceedings of Learned Societies. 
communicates, by means of a2 joint, with 
a crank. congeéted with a wheel, which 
gives the water-wheel a motion fomewhat 
flower than its own ; at the fame time the 
water-wheel ferves asa fly. The fleam- 
engine differs but little from that improv- 
ed by Boulton and Watt. There is, how- 
¢ver, an apparatus for opening and fhut- 
ting the cocks at pleafure, in order to re- 
vert the motion of the boat whenever it 
may be neceflary. 
The water-wheel] is fituated near the 
ftern, and in the middle of the breadth of 
the boat, fo that it becomes neceflary to 
have two rudders, connected together by 
rods, which are moved by a winch near 
the head of the boat: by this means the 
perfon who attends the engine is able to 
fteer alfo. 
Another material part of the invention 
confifts in the arrangement of ftampers, at 
the head of the boat, fcr the purpofe of 
breaking the ice on canals. Thefe are 
raiied in fucceflion by means of levers, the 
ends of which are deprefied by the pins of 
wheels turned by an axis communicating 
with the water-wheel. It has been cal- - 
culated that a boat, doing the work of 
twelve horfes, may be built for eight or 
nine hundred pounds; and by experiment 
it is known that it will travel at the rate of 
two miles anda half per hour. 
In Dr. YouncG’s Summary of the moft 
uféful Parts of Hydraulics, extracted and 
abridged from a German work of Ey- 
telwein, we have an account of the /piral- 
pump, which is a pipe wound round a cy- 
linder, the axis of which is horizontal, and 
one end connected with a vertical tube, 
while the other is left at liberty to turn 
round and receive water and air in each 
revolution. This pump was invented 
about half a century ago by Andrew 
Wirz, a pewterer in Zurich, and was 
employed at Florence, with fome 1mprove- 
ments, by Bernoulli, in- 1779. Dr. 
Young tells us, that Mr. Eytelwein enters 
very minutely into calculations of the ef- 
fe& of fach a machine, under different 
circumftances ; and the refults of theory, 
as well as experiment, are fuch as to in- 
duce him to expect that it will in time 
come into common ufe, inftead of forcing- 
pumps of a more complicated and expen- 
five conftruction. 
Dr. Young does not feem to be aware 
thar a pump of this kind has been in ufe 
for more than twenty years in this coun- 
try. At Chevening-houfe, in Kent, the 
writes of this article has feen and greatly 
[Nov 
admired the beautiful fimplicity and great 
regularity with which water is eonduéted 
to different parts of that building, by 
means of a-fpiral-pump. “Water is the 
force employed in turning the wieel. 
- -CHEMISTRY. 
We learn from “ the New Experiments 
on Artificial Cold,” by M. Lowitz, a 
particular account of whicn will hereafter 
be publifhed in the Tranfaétins of the 
Academy of Peterfourg; 
1. That the principal ecaufe of the cold 
produced during the folution of falts in 
water, depends upon fome agency of their 
water of cryftallization ; for falts deprived 
of this water, inftead of producing cold, 
produce heat. ‘ 
2. Amongft the liquid acids, the mu- 
riatic acid is mofl efficacious for form- 
ing freezing mixtures ; the nitrous acid is 
next to it inorder ; and the fulphuric acid 
is leaft powerful. — 
3. The liquid acids produce cold only 
becaufe they cceafion a quick folution of 
the fnow, or falt, of the freeezing mix- 
ture. 
4. Cauftic potafh and the rauriate of 
lime furpafs very much, as cooling 
agents, the acids and the other faline fub- 
ftances. . 
g.. The bef proportion ‘of the mixture 
of (now and muriate of lime, is two parts 
of the firft to three parts of the Jaft, mixed 
as accurately as poffible. . 
6. Five pounds of muriate of lime are 
fufficient to freeze thirty-five pounds of 
mercury. 
7. The deliquefeent falts are much 
more proper for producing cold than the 
efflorefcent falts. whey: 
8. That the deliquefcent falts may 
produce the higheft degree of cold, it is ne- 
ceflary that they contain the greateft pof- 
fible quantity of water of cryftallization ; 
and that they be ufed in fine powder. 
g. The fnow employed fhould be that 
which has newly fallen, light and dry ; 
and the experiments fhould be made at the 
commencement of a froft, and not during 
a thaw. 
1o. It appears that the fuperiority of 
the deliqueicent falts to the acids is ow 
ing to the circumitance of their becoming 
fluid at the fame time that they caufe the 
fnow todiffclve. : 
11. Cauftic potafh and muriate of lime 
poile{s, amongft other advantages, that 
of being eafily: reftored, unaltered, to their 
folid fate, after an experiment, by evapo- 
ration. 
NEW 
