‘ Vi ngdom.]

AND SURGICAL INSTRUMENTS.

North, North Central, and South Central Galleries.

415

■wheel

Whe i lc,ulves - The fuzee-wheel has 90 teeth, centrepiiii centre pinion 14, third wheel 80, third

Til ,.; 011 1 -> fourth wheel 80, fourth pinion 10, and ’scape

3« 10 ’-’ SCa P e - whee115 -

Wat L pecimens g°lfl pocket chronometers and leverWitL • ’ re( luced from the calibre of the chronometer;

and* T'jO'ovements in the form of the teeth of wheelsatt., P' nions > in the balance-springs, and in the mode oftt 4 ac hing the spring.

of j 1 ae double rotatory escapement. This is a specimen*hav >'. eW ca iihre movement, by which a powerful watchkeen 4 nia ^- e i n a fl at case; a method which might havei n t r ?fl°pted at the period when flat watches were firstbytav Ce ^’ as ^ as t ' le advantages of a thick watch,a s tv, the contents of the barrel in diameter and depth5 pi * S °f power.

(1 0 |,1| ay^of-the-month watch, with lever escapement andUt e . r ollers. The calibre of this watch may be calleddo e . Slln ple than the preceding one, only because it more°f tli res cmbles that which is daily made. The numberl s e teeth of the wheels is peculiar. The centre-wheel10 U i • en larged, with 100 teeth working in a pinion ofteeth Ulst the third wheel is diminished, which has 60teeth . Woi ' k tng in a pinion of 10; the fourth wheel 63oalib m a Ptnion of 7. Although this is a good workingb e re ,for a superior watch, yet if power is admitted totatnePP lnc ipl e in watch-making, it is impossible to get theNo ^ . Pth of barrel in this wa

h av a Producing the foregoing calibres, all technical sizes*»ch been rejected, and the common measurement ofs 0 J" s > tenths, hundredths, and thousandths adopted;n^at f rom one ca i;bre, a watch of any size may beg e Ay proportion.

cent *P ec >men of gold lever watches, with the split-Co filn? sec onds-hand movement. This watch, being acise ?■ e time-keeper, is capable of determining the pre-m ea °f any observation to a quarter of a second, byv ’ded S ° P an extra seconds hand, with which it is pro-Un d ’ and which in the ordinary state of the watch liesj Q r the principal seconds hand, and travels with it.s tead'f a k* n ® an observation, the observer keeps his eyeto flyfixed upon the object, and his finger in readinessfa)) ac " a spring, which allows the registering hand tom ay ® lni ultaneously upon the face of the watch, where it' a R off a fl owe d to remain upwards of 40 seconds for read-h>edi tlle time; this being done, the finger is to be im-i,, s *ately removed in order to free the register, whichv atio tly ret urns to its place ready for the next obser-ve c ’ wit hout having in the least degree interfered withy ’'rrect performance of the watch.if Specimen of railway watches.

P ° c ’ aien °f English pinions for astronomical clocks,<j lri g the true curve of the teeth,lo' oP ec ! me n of carriage clocks.

Il‘ Specimen of portable chime clock.

12 SP. ec ™ en of chronometer and watch movements.

13 ^.grains of calibres of chronometers and watches,tho 11 1 Ganges for admeasurement of watch-work to the

^sandth of an inch.

15 - ,.P ec imens of gold watch cases.tuv e of ” e new calibre, by means of which the manufac-aiid f a .patches and chronometers is greatly improvedThe e^i'tated, and the expense considerably reduced.

l6_ p- ln the preceding page represents this new calibre.c °nnio„ lVa st ages of the process of manufacture in the17 Pensation balance.

^ktrenie ux j.flary compensation for the adjustments of thes °f temperature.

C W'er u." . ....

it ; s Q „ ocmg an indispensable element m time-keepmg,

he tr an a titmost importance that the motive force shouldto Pinio mitte ^ w tth a constant velocity-ratio from wheelhy f] le ? throughout the train, without its being absorbedProne,. lncrea sed friction and wear consequent upon im-1'he Urves *

ago ( by C p lec l fot'ms of curve were described, a century'Wans, and recently in a work on the Principles

ls used.

i watch, unless the calibre of

of Mechanism, by Professor Willis, of Cambridge, 8vo,London , 1841.

In watch-work, the wheel is the driver, and the ad-dendum to the tooth beyond the pitch-line is of the epi-cycloidal form, which, to the general eye, may be fami-liarly explained as resembling a Gothic arch, or a bishop’smitre. The pinion is the follower, and has the twoflanks of its leaf formed by radial lines direct to thecentre; and the addendum upon the pitch-line is a semi-circle whose diameter is the breadth of the leaf. Thespecimen will explain the rest.

The new calibre by the exhibitor is shown as a generalimprovement in chronometers and watches.]

Fig. :

60 Hall, George Fredbrick, Norfolk StFitzroy Square —Inventor.

An astronomical and meteorological clockfor mean time, and for registering the hourlyvariations of the barometer and thermo-meter. The escapement of the clock is anew vertical dead-beat escapement; the pen-dulum has a new micrometrical compensa-tion adjustment for temperature, intendedfor the self-registration of natural pheno-mena.

Fig. 1 is a plan of the escapement, half-size. A is a vertical wheel of seven teeth,which move in a horizontal plane. B is aconcentric circle, with two ruby pins movingin a vertical plane; if the pins are circularor chamfered, the action is dead during thecoincidence of the two planes; but as thepins vibrate, the top of the teeth strike, andescape, and slide, under the circular orchamfered surface of the ruby pins, andgive the necessary impulse to the pen-dulum.

Fig. 1.

T

Fig. 2 is the pendulum with the micro-metrical adjustment for temperature, whichis effected by a compound rod of brass andzinc, in the proportion of 20 brass and 10zinc, joined just above the bob; a zincscrew is soldered into the top of the brasstube, and a steel screw into the zinc cy-linder, both of the same pitch. The lengthof compensating rod is first obtained bycalculation; then, if the pendulum is com-pensated plus, the rod is turned to theright, which shortens the zinc screw, andincreases the steel; the difference betweenthe expansion of zinc and steel is theamount rendered minus in the compensa-tion. If the pendulum is compensatedminus, the rod is turned to the left, which increases thezinc, and shortens the steel; the difference of expansionis the quantity rendered plus. The pendulum is made oftwo glass tubes expanding downwards, and the compoundcompensating rod expanding upwards; the bob being placedupon studs fastened to the inner glass tube, and passingthrough the outer. The black line in the drawing is thecompensating rod.

Fig. 3 is the elevation of the clock one-eighth real size,with the dial-plate removed, showing the meteorologicalregistering apparatus. A a are two revolving cylinders