50 
a comparatively low temperature will pro- 
duce all the effects that can be obtained 
from fteam of 2 high temperature, with- 
out any of the rifque with which the pro- 
duction of the latter is accompanied, not 
only to the boiler, and other paris of the_ 
machinery, but even to the lives of the 
workmen. ; 
Ancther improvement mentioned in this 
fpecification confifts in a method of pre- 
venting, as much as poffible, the paflage 
of any of the fteam from tint fide of the 
pitton which is a&ed upon by the faid’ 
fteam to the other fide which is epen to 
the condenfer: this is effected in double 
fteam-engines, by employing upon, or 
about the pilton, mercury; or Auid me- 
tals, inan altitude equal to the preffure of 
the team: thus when the pilton 1s afcen.t- 
ing, the fpace on its other fide being open 
to the condenfer, the iteam endeavouring 
to pafs up the fide cf the pifton is met, 
and effectually prevented by the column 
of metal equal cr fuperior to it in pref- 
fare, and during the dvwn firoke no fteam 
can poffibly pafs without firft forcing all 
the metal through. In working a tingle 
efgine, a lefs confiderable altitude of me- 
tal is required, becaufe the fteam always 
atts-on the upper fide of the pifton.— 
Care mut be taken that the outlet that 
conveys the fteam to the condenfer tbe fo 
pofited, and of fucta fize, that the {team 
may pafs without forcing betore i:, or car- 
rying with it, any of the metal or other 
fubitance employed that may have pailed 
by the pitton ; taking care alfo to provide 
another exit for the metal or other firb- 
flance collected at the bottom cf the fieam- 
veflel or working cylender, to convey the 
fame into a refervoir kept at a proper heat, 
whence it is to be conveyed to the upper 
fide of the pifton by a imal! pum», worked 
by the engine, or by any other contriv- 
ance. ‘To pievent the fluid metal from 
oxydating, fome cil, er other proper fluid 
febftance is kept on the furtace, to pre- 
vent its coming in contact with the atmo- 
fphere; and to prevent the neceflity of 
empisying large quantities’ of fluid ‘me- 
tal, the pilton is made at the dept» of the 
column required, but of a diamcter-a lit 
tleJefs than the ftcam veile] ot working 
cylender. Oil is alis employed ‘in: the 
ipper part of the tebe or pipe attached 
ro the team-vefiel; by which means 
feem of any. temperature may be ufed 
witheut beme expofed to the rifque ¢f par- 
tial condenvation, by the admiflion of any 
colder body into the team-veffel, for the 
oi ivon acquires the requifite tempera- 
ture 5 arid to prevent an unneceilary eicape 
New Patents lately Enroll-d. 
[ Feb. 4, 
of heat, imperfect condu€tors are ufed to 
line that part of the tube or pipe attached 
to the fteam-veflel, which may be heated 
exteriorly, 
ae 
MR.HAWKINS’S (GOLDEN-SQUARB), for 
an Invention applicable to mufical Infiru- 
ments, the Principles of which may be 
apphed to various other Machinery. 
We can but barely enumerate the heads 
of the feveral inventions deicribed in the 
fpecifcaiion now belore us, Tne firt of 
which confiits in metailic rings made with 
fpirat or curved wire, or with links to 
produce bafs found, which occupy a 
thorter {pace than is ufual, Thele trings 
may Qe applicd as bands for the turnisg 
of wheels and other machinery. (2.) Gut, 
, or Gik, or other ‘ttrings are to be rendered 
water-proof, by being impregnated with 
drying oils, &c. defigned to refift the 
‘action of the atmofphere, by which ftrings 
are frequently put out of tune. (3) The 
firings of piano-fortes, and other finger 
keyed-inftruments, are to be fixed in a 
perpendicular pofition, by which the fhape 
of the infruments will be moré elegant 
and convenient.- (4.) One end of each 
firing of all mufical inffruments is to be 
connected with a f{pring, or fuzee, or le- 
vers, to which the {pring is fixed, fo that 
the {pring fhall aét with equal force in the 
tring when it contracis or expands; this 
principle is to be applied to the equaling 
of any irregular power, fuch as the action 
of the winds. (5.) For the purpefe of 
tuning the ftrings of mafical inftruments, 
there are to be fliding frames or carriages, 
each worked by a fcrcw, in a frame of - 
metal, to which a frimg is attached. 
(6.) There are to be attached to harps 
and other inftruments, where it will ap- 
ply, a roller, worked by a pedal or pedals, 
having pins or other projections, aéting 
upsn levers, which prefs on any of the 
firings at the plealure of the performer, to 
vary the tones by fhortening the vibrating 
part. (7-) There is alfo to be affixed to 
inftvuments from which the tones are pro- 
duced by hammers, a roller made to turn 
with confiderable velocity, having projeét- 
ing parts to firike by levers on the tail of 
the hammer, to make it.continue ftriking 
the itrings {fo long as the inger-key is kept 
down. (8.) All miufical ftringed inftru- 
‘ments are to be made without any box or 
hollow fpace under the  fownd-board. 
(9-) ‘Phetone of the vibiating body is ta. 
be lengthened by the revolution of a hoop 
or ring, on the infide of whjeh hails are 
ftretciied in equal chords of the circle, in- 
ievlecting each other, and forming a tga | 
ar 
