AND SURGICAL INSTRUMENTS.
Noktii, North Central, and South Central Galleries.
413
Kini
gdom.]
Tawinder, —, Rotherham —Manufacturer and, _ Designer,
n eight-day skeleton clock with lever escapement.esi gn taken from Rotherham cathedral.
°5 Dent, Edward John, 61 Strand , 33 Oockspur Street,a ‘id 34 Royal Exchange —Inventor and Manufacturer,tjjg’P°ld “tac” watch. The term “tac” implies thatt e _ , me is ascertained by turning round the large ex-) 5 n al g°id hand until it is stopped. The time is thene ' Vn by determining the place of the hand with refer-h v to the twelve projecting nibs on the edge of the casenjj be touch. The interval of time can be thus deter-Su ea to about a minute. This description of watchd e ? erset ^ es the usual striking repeater, is less liable tothe a >i 1 ® ement ’ an< I ' s ^ ess ex P ens * ve - It is wound up andn bands set without the usual detached key.ino'- aiIn ' la '' watch, with hunting-case, and small open-- S m the centre to know the time without opening the
cover.
to ’ .Unnting cased watch, with case springs outside, andjj 0r Wm( I up and set the hands without a detached key.Wh: J* se tn India , and may be considered air-tight, by^ c b arrangement frequent cleaning is avoided.
&c " °P en -faced watch, with compensation-balance,
j p specimen of the best description of English watch.s eco n watc b. with compensation-balance, &c., and twos tat' S ” hands in the centre. The under one (as shown°U T,' ll,a - y 'he 45 seconds or minutes) drops instantlyThf ressin g a nib at the end of the pendant of the watch,lute f ux 'I' ar y hand remains still as long as required,of ,• ed for delicate experiments where small intervalsg 1B J®, are required to be noted,hu/ Phased watch, with compensation-balance, &c., hav-aj.® a ar °P seconds’ hand. It is wound up, and the handsof t f et > without the usual detached key; made for the sonViceroy of Egypt .
a sn •“graved watch, with compensation-balance, &c.;
1 ""finen of watches intended for the Spanish market.tii e ,’ i Watches, with compensation-balances, as speci-10 w tbe 'I' urk i s h market.
"inis' I. a 'ch, with compensation-balance, &c., as a spe-jjb ™ r the Persian market.
12*, atch, with compensation-balance, English style.
I ’ '1. Ladies’ watches, with compensation-balances, &c.15 - Ladies’ gold watches of the usual construction,bau’ 1? - Gentlemen’s gold watches, with compensation-{*<*«, See.
tion 1 - 9 ’ 20 - Gentlemen’s watches of the usual construc-21 "ivr llout c °mpensation-balances.gl as ’ Marine chronometer, with a glass balance-spring,"'"an balance > and compensated, for temperature, byha s b ° f P lat ' num and silver. This glass balance-springll.\j een tried at the Royal Observatory, and on boardtic a i Ar Uvey ' n S ship, “Fairy ” (for official rates, see “Nau-
22. p a f azille ’” xxix )-
spr; n d ("nt marine chronometer, having the steel balance-23 S ’ Jplded. by the electro-metallurgic process.c °tnt)p A a ^ nt marine chronometer, having a secondaryIr >U(te by which the compensation weights are
the m.- 0 ni0v e so as to counteract the effect produced by
24 temperature.
25 a ar * ne chronometer of the ordinary construction.
c °mpass which can be inverted; the magneticare etl are P^ a ced on a vertical axis, and the divisions§ av ?^ 0n both sides of the silver ring (or compass-ot her’ a 2 f oue reading can be made before, and theVea du inversion. The mean between these two
*We t g e fves the error of the zero on the card; there-Ca n be (t e ^ rae . ma 1 S uet ic bearing of any observed object
CTh, ^
uermined.
C ° ttl Pass < ' r ^ nar ^ way the card and needle of a
1'he !? u P°n an inverted cup resting on a fine point.Passes S 1Catl0n the chronometer suspension to com-as above, is with the view of avoiding the great'’filiation* 5011 ^ ne P°' n ', caused by great vertical
26. An azimuth and altitude compass. The principleis the same as in the former, with the addition of atelescope carrying cross wires, and a divided arc foraltitudes; the rays from the observed object pass throughthe telescope, whilst those from the card, reflected bythe prism, pass to the eye of the observer.
27. A steering compass, with the needles gimballed ona vertical axis, by means of which the effect of the violentmotions of the ship on the compass-card, and the effectof variation of dip, are neutralized. The superiority ofthis over the ordinary compass, in which the point ofsuspension of the card is higher than the centre of gravity,is most evident in steamers where the speed is great, andwhere the motion occasioned by the sea, as well as thatfrom the vibration of the engine, disturb the usual com-pass-card, which obeys the laws of a pendulous body;whilst the compass-card placed on a vertical axis is notdisturbed from any such causes.
28. An eight-day quarter striking turret clock, withcompensated pendulum, 8 feet long, and weighing above2 cwt.; vibrating half seconds, with pin-wheel, and deadescapement, but with a small recoil. All the wheels inthe clock are of cast-iron, except the ’scape-wheel, whichis brass, of only 4 inches diameter, containing 40 pins,and turning in 2 minutes.
The ’scape-wheel is driven by a small spiral spring fixedto a pinion, which turns on a stud set in the same line asthe ’scape-wheel arbor, and carrying one of the pivot-holesof that arbor. This spring is wound up a quarter of aturn by the clock, at every quarter of a turn of the’scape-wheel.
The dial-work is all driven by the great wheel, withoutthe intervention of any pinion, and it is consequentlyvery strong, and capable of working four very large dials.The dials in the great avenue of the Exhibition are 7 feetin diameter. The hands are adjustable by means ofhand-screws, and a small regulating-dial set on the clock;this dial is reversed, in order to provide for the case ofthe external dial being on a level with the clock, and thehands driven directly by the prolonged arbor of theregulating-dial. The hands are counterpoised outside thedials; because, when the counterpoises are within, theforce of the wind on the hands is not counterpoised atall; and the weight of a large hand, when unbalanced,tends to loosen the hand on its arbor, and so make itpoint behind the true time from 6 to 12, and before itfrom 12 to 6.
The maintaining power for keeping the clock goingwhile winding, is of a new construction. Before winding,the maintaining weight must be raised sufficiently highto keep the clock going about seven minutes, and whenwound up, it can be thrown out of action immediately.
All the great wheels are set in the great frame, and thesmall triangular frames can be taken off without movingthe great wheels and barrel, or the pendulums, whichmay also be suspended from the wall. The smallerwheels will also take out separately. The weights arehung by wire ropes, and they require a fall of about40 feet, with a single pulley. The pulleys are 1 footin diameter.
The hammers are raised by cams cast on the greatwheels, of such a shape a3 to raise them with the leastfriction. They are strong enough for an hour-bell ofseveral tons weight, and quarters to correspond, thoughthe great wheels are only 18 inches in diameter. Thehammers all stand ready to fall as soon as they are dis-charged by the going part. The 1st, 2nd, and 3rd quartersbegin exactly at those quarters; the 4th begins half aminute before the hour, and the hour-hammer fallsexactly at the hour. .
The object aimed at in this clock, is to combine thegreatest accuracy of time-keeping with great strength,and the cheapest mode of construction which is consistent
29. A patent dipleidoscope, to be used as a fixed men- •dian instrument. 4 he optical airangement consists intwo silvered parallel reflecting glasses placed at an angleof about, 60° behind the front glass. The image of thesun is reflected from the front glass, and the sun’s rays