THE advance of physical science receives its illustration in a variety of directions among the objects collected together under this Class. The progress of experimental philosophy may be gathered, in a degree, from the perfection of the instruments it employs; for while it is certain that in some sciences much has been accomplished by the aid of rude and imperfect means, it is equally true that in others the perfection of the apparatus is essential to that of the knowledge sought to be established by deductions drawn from its indications. The delicacy of a balance is necessary to the accuracy of a chemical experiment, and therefore to that of the facts it is used to develop, as also is the achromatism of a microscope, or a photographic lens to the development of the optical images, and to the results sought to be obtained therefrom: chemistry, microscopical sciences, and photography, are consequently largely dependent for their progress upon the instruments by the use of which they are to proceed. The same cannot be said of surgical instruments, for in their use the operator may command success by his skill, notwithstanding the imperfections of his apparatus. Nevertheless, the present state of surgery, and the attention bestowed upon it, may be gathered from the inspection of the refined and complicated apparatus offered for its advancement. As one of the results of the splendid and enduring system of knowledge, and of its pursuits-promulgated by Bacon in the "Novum Organon," the system since called Experimental Philosophy-objects in this Class wear a peculiar interest, representing the means employed by man for the establishment and development of inductive science.

This Class includes instruments employed for a variety of philosophical purposes; it also comprises musical, horological, and surgical instruments and apparatus. It may consequently be considered under three SubClasses. The first comprehends-A. Instruments for the measurement of space, such as Transit Instruments, Quadrants, Sextants, Telescopes, Microscopes, Theodolites, &c.; B. Instruments to measure the effects of mechanical and physical forces, as Dynamometers, Balances, Thermometers, &c.; C. Instruments to illustrate the Laws of Mechanical and Physical Science; D. Application of mechanical and physical science to useful purposes not included in any of the preceding or subsequent sections, such as instruments connected with Mechanics, Sound, Light, Heat, Magnetism, and Electricity; E. Comprehends Chemical and Pharmaceutical Apparatus. The Sub-Class, Musical Instruments, comprises-A. Wind Instruments, in wood and metal, as Flutes, Bassoons, Horns, Trumpets, &c.; B. Stringed Instruments, as Harps, Guitars, &c.; C. Keyed Instruments, with fixed tones, such as Organs, Pianofortes, Accordions; D. Instruments of percussion, as Drums and Cymbals; E. Automatic Instruments; and F. Miscellaneous articles in connexion with musical instruments. The Sub-Class, Horology, contains-A. Great Clocks for Churches and Public Buildings in general, including Electric or Magneto-Electric Clocks; B. Astronomical Clocks; C. Clocks applied in registration. D. Clocks showing different phenomena; E. Clocks for ordinary purposes; F. Clocks of an ornamental description; G. Sundries applicable to clocks; H. Marine Chronometers; I. Pocket watches of various descriptions; J. Watches for different markets. The remaining Sub-Class, Surgical Instruments, includes a variety of apparatus adapted to the performance of operations in different parts of the human body, together with the philosophical apparatus employed by the surgeon in the investigation and treatment of disease. It also embraces the instruments employed in Veterinary Surgery.

The large astronomical telescope in the Nave, mounted upon a stand, having equatorial movements and complete adjustments, is an interesting member of this Class. It is a refracting instrument, and possesses an object-glass nearly 12 inches in diameter. Telescopes of a smaller calibre, and adapted for different purposes, are also exhibited near it. But the general arrangement of the objects representative of this Class is to be sought in the Central North Gallery. This gallery is reached by ascending the stairs near the North Transept. On entering it, and proceeding past the articles in glass, which are also placed here, the commencement of this Class is met with at Area I. 22. From this point it extends to the western termination of this gallery. The interspace between the North and South Central Galleries is also devoted to it, and a portion of the South Central Gallery, from M. 3 to M. 8, contains various articles included in this Class. Proceeding westward, in the Central North Gallery, musical instruments are first encountered, including a variety of organs, harps, pianos, &c. Succeeding to these are philosophical instruments, electric telegraphs, daguerreotype apparatus, and specimens of photography: beyond are globes and astronomical apparatus. In the South Central Gallery are watches and clocks. A part of the North Gallery, devoted to surgical instruments, and occupying the space between F. 15 and F. 21, also belongs to this Class.

NORTH, NORTH CENTRAL, AND SOUTH CENTRAL GALLERIES.

The science of horology is illustrated on the great as well as on the small scale in the large clocks and the minute chronometers exhibited in this Class. The large electric clock, the hands of which are seen projecting over the south entrance of the Transept, is an interesting example of the application of the force of electromagnetism to move mechanical arrangements for the measurement of time. A small galvanic battery keeps this large instrument, and several other clocks in the Building, in regular movement. The ribs of the Transept have been made to represent the dial, and show the hours from 6 A.M. to 6 P.M. Other electric clocks on a smaller scale are shown, and exhibit various ingenious arrangements intended to effect the same end. Selfregistering, astronomical, and other clocks are likewise exhibited. In some of the large clocks for churches and public buildings, one of which is in the Nave, and others are at the termination of the Galleries, new principles of suspension and compensation of the pendulum and of escapement are introduced. Much ingenuity has often been expended upon clocks with a view of communicating to them the power of indicating, in addition to ordinary time, that of different places, and of different periodical occurrences, as the rise and fall of the tide, the day of the month, &c. Several of these clocks are shown, and particularly one which occupied its patient constructor thirty-four years in its manufacture. The watches and chronometers exhibited have also their peculiar claims to attention. The escapements of some of the latter are in part new, and appear to promise favourable results. Several different specimens of watches, adapted for different markets, afford a curious illustration of the variation of natural tastes-the variety of methods in which compensation for the changes resulting from variations of temperature is obtained both in chronometers and in astronomical and other clocks. Extremely small watches, as specimens of minute workmanship, are exhibited. The parts of watches and clocks are likewise included in this Class.

The philosophical instruments exhibited comprise a large number connected with the display of the phenomena of heat and electricity: the aneroid barometer, in which the mercurial column is dispensed with, and various forms of the ordinary barometer are among them. Electric communications are now effected by a variety of apparatus of greater or less facility of application. Printing electric telegraphs, in which a message is recorded by this agency, upon a chemically-prepared paper, appear in various forms with the ordinary needle telegraph. The methods of electric insulation for telegraph uses are also exhibited. Among these will be regarded with interest the wires adapted for submarine communication between this country and the Continent. The magnetic and electric machines, with electro-magnets of great power, are also interesting.

British manufacturers have for some time been making great efforts with a view of producing good optical glass, and a skilful method of working it into the forms desired for optical purposes. These efforts have been* so highly successful that the glass produced in England is not unfrequently exported and again re-imported as foreign glass at a much higher price. The production of lenses has also greatly improved; and achromatic glasses of considerable size, as well as of a smaller kind, are made with success in this country. Microscopes, telescopes, and the minor philosophical instruments, are now of excellent quality and highly-wrought character.

Photography is included in this Class, both on plates of silver and glass, and on paper. The most beautiful specimens of sun-drawn pictures are exhibited. Daguerreotypes of every kind, plain and coloured, "enamelled," and " crayon,"-improvements of recent introduction, and applied to a variety of purposes,-are found here. The largest daguerreotype probably yet produced, a group of sculpture, is placed in this Class. The talbotypes are also very beautiful, and present a charming evidence of the fidelity and artistic effects capable of being produced by the pencil of Nature. Photographic apparatus of various kinds, together with the results of curious photographic experiments, illustrative of the distinct existence of luminous and actinic rays in the solar beam, are also represented.

A great variety of miscellaneous philosophical apparatus, for popular illustration, and for the purposes of the experimentalist, is also displayed, and must attract notice. The musical instruments exhibited include several powerful organs. That over the West Entrance possesses 80 stops. The organ over the Eastern Entrance exhibits a new and pleasing arrangement of pipes, and possesses a powerful set of stops. The organ over the South Transept Entrance is devoid of a case, and exhibits the internal mechanism; it possesses a powerful reed stop, and other stops. Pianos, harps, seraphines, of new modes of construction, and decorated in a remarkable manner, are likewise found here. The instruments of the surgeon have a purely professional value, and will be sought by those interested in that pursuit.

Regarding this Class as representing the culminating point of mechanical skill, it forms an appropriate conclusion to those devoted to machinery generally. Delicacy and precision of workmanship are absolutely requisite in the industry occupied in producing philosophical apparatus. It will be found, on inspection, that the genius of this country, so remarkably developed in mechanics applied to commercial purposes, is not less successful in its application to the higher pursuits of experimental and practical philosophy.-R. E.

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NORTH, NORTH CENTRAL, AND SOUTH CENTRAL GALLERIES.

BENNETT, JOHN, 65 Cheapside-Inventor and

Manufacturer.

A regulator, which beats half-seconds, with mercurial pendulum; adapted for reading-rooms, railway stations, and other places where an exact time-keeper is required at a small expense, and where economy of space is an object.

Hall clock-in a carved oak case, of new design; chiming the quarters, and striking the hours on a gong. Finished specimen of marine chronometer.

Model watch, on a magnified scale; constructed to show the most compact form of the modern watch, with all the recent improvements; to which is attached a peculiar mode of regulation, by which the wearer, with one touch of the regulator (fixed on an endless screw) can correct any variation of time.

Model watches in gold cases for pocket use; jewelled in thirteen holes. Comprising, in a simple form, essentials for its correct performance in all climates; with a gold chain of new design. Exhibited to show the introduction of a variety of ornamental detail, coloured by means of different bases of alloy, without the aid of either enamel or precious stones.

Time-keeper, for railway guards, constructed to combine cheapness, strength, and exact performance.

Specimens of standard thermometers, with ivory and box-wood scales.

Bennett's registered illuminated night timepiece, attached to a Palmer's candle lamp, by the burning of which a spring gives motion to the hands of the dial with great exactness.

Carriage clock, in rosewood case, with detached lever escapements and compensation balance.

A regulator, beating dead seconds, with mercurial pendulum, in the simplest form of case and movement compatible with strict nicety of performance.

Cathedral clock dial of plate-glass, and of new design; weather-proof; with a movement in action.

A wind dial in action from a vane above the roof of the Exhibition Building, with a self-recording machine for registering the wind's force.

2

ADAMS, F. B., & SONS, 21 St. John's Square,
Clerkenwell-Manufacturers.

No. 17. Silver pair of case watch; vertical escapement. Nos. 15, 16, and 17, are used by artizans and labourers. No. 18. A three-quarter plate finished movement lever escapement; eight holes jewelled, gold balance. This description of movement is adopted for the purpose of obtaining a thin watch.

No. 19. A full plate finished movement, lever escapement, eight holes jewelled, compensation balance, &c. No. 20. A finished movement, vertical escapement. The same workmen, in their various branches, were employed upon No. 1, the largest, and No. 11, the smallest of these watches.

Description of Compensation Bar.-1. The compensation bar consists of two bars of brass and iron, 10 feet 1.5 inch long, 0.5 inch broad, and 1.5 inch deep, placed 1:125 inch apart, supported on brass rollers, at one-fourth and three-fourths of their length, and firmly fixed together at their centres by transverse steel cylinders 1.5 inch in diameter, and being free to expand from or contract towards their centres independently of each other. At the extremity of, and at right angles to, each of these bars is a flat steel tongue, 6.2 inches long, 1.1 inch broad, and 0.25 inch thick; projecting 3.25 inches on the side of the iron bar, and moving freely on conical brass pivots, rivetted into the brass and iron bars, each axis being perpendicular to the surface of the tongue, allowing it to be inclined at slightly different angles to these bars, according to their expansion from, or contraction to, their centres. The centres of the two axes are at 0.5 inch and 2.3 inches from the end of the tongue next the brass bar. On the tongue, and flush with its upper surface, near the extremity, is No. 3. Gold watch; enamel dial, first class, three-inserted a silver pin, with a dot marked on it, as the comquarter plate movement, duplex escapement, 10 holes jewelled, compensated balance, &c.

No. 1. Gold open-face, double-back, cased watch; enamel dial, first class, full plate movement, lever escapement, capped, eight holes jewelled, and compensated balance, &c. This description of watch is used in the northern states of America.

No. 2. Similar watch, with gold dial. This is made at one-third the cost of Nos. 1, 3, or 8.

No. 4. Watch like the preceding; three-quarter plate movement, lever escapement, five holes jewelled, and gold balance.

Nos. 5, 6, 7, 8. Gold watches; first class, three-quarter plate movement, lever escapement, full jewelled, compensated balance, &c.

Nos. 9, 10. Gold watches; gold dial, full plate movement, lever escapement, jewelled, plain balance (for ladies).

Nos. 11, 12. Gold watches; first class, three-quarter plate movements, lever escapement, eight holes jewelled, compensated balance, cases enamelled, and ornamented with diamonds.

No. 13. Gold watch; enamel dial, showing seconds from the centre, without additional train.

No. 14. Gold, engraved, double-back, hunter-cased watch; first class, three-quarter plate movement, duplex escapement, 12 holes jewelled, compensated balance. This description of watch is used in the East Indies, Persia, Spain, and South America.

No. 15. Silver, open face, double-back, cased watch; lever escapement, capped, and four holes jewelled.

No. 16. Silver hunter engine-turned watch, vertical escapement.

pensation point.

The bars are placed in wooden boxes (made of wellseasoned straight-grained deal), to the bottoms of which are fixed the plates that hold the brass rollers on which they are supported, and having in the middle a vertical brass stay, screwed to the box, and passing upwards between two steel cylinders, to prevent the bars being moved longitudinally in their casing. To protect the tongue carrying the compensated point (which projects beyond the wooden box) from injury, nozzles are fixed to the boxes, having a small circular orifice with a lid on the upper side to allow the dot, or compensation point, to be

seen.

On one side of the connecting steel cylinders, and attached to the brass bar only, is placed the longitudinal level, the lid of the box being furnished with a glass window and shutter, to enable it to be observed. Over the rollers which support the bars are two pieces of metal, for preventing any sudden jar from striking the bars against the lid of the box. At each end, on the outside of the bar-box a thick metal plate is screwed, for the purpose of firmly fixing a three-armed groove-stand, intended to support the tripod of the compensation microscope; and at each end of the box are two vane sights (which shut down with hinges into grooves), used for placing the bars approximately in line.

NORTH, NORTH CENTRAL, AND SOUTH CENTRAL GALLERIES.

On both sides, at one-fourth and three-fourths of the length, are brass plates, with holes for receiving the screw which clamps the plate of the tripod-stand (technically called a camel) to the box, for the purpose of adjusting the bar in a longitudinal direction. The compensation bars are six in number; the weight of each bar, with its two brass ends, is 136 lbs.

Description of Compensation Microscope.-2. The compensation microscope consists of three microscopes, placed three inches from centre to centre, connected by two bars of brass and iron, 7 inches long, 0.6 inch broad, and 0.375 inch thick, 2.5 inches apart, firmly secured together by means of a brass collar and cylinder, forming part of the tube of the centre or telescopic microscope.

under the table, which is 2 feet 11 inches in height. Under the body of the table and in the centre there is a square box of 16 inches in all directions, with 4 exterior and lateral divisions of 2 inches in breadth each, 16 inches in length, and 8 in depth, for receiving the cases of amputating, trepanning, miscellaneous, and cupping instruments, and they are exteriorly so marked. When amputation of the thigh, or any other extremity is required, the necessary instruments are laid out on the inside of the cover of the box just adverted to, beginning with the letter nearest to the limb to be removed, the first instrument wanted to be placed opposite A, and the second opposite B, and so on, according to the order in which they are required during the operation. If a shoulder is to be removed, the same arrangements are to be adopted as in the amputation of a thigh, with the difference of placing the instruments at the head instead of the lower extremity of the table. The divisions in the centre are intended to receive bandages of 6, of 5, of 4, and 3 yards in length, and 3 inches in breadth, and they are capable of giving accommodation to 200 of the description noticed. The drawers in front marked ligatures are intended to keep these essential agents of surgery in constant readiness. The drawers marked slips of adhesive plaster indifor operations and wounds. The compartment marked cate the propriety of their being at all times in readiness fractures is for keeping the splints and bandages necessary marked dislocations indicates that all instruments refor the treatment of such accidents. The department quired for the reduction of such dislocations are there to

The two bars, carrying with them the outer microscopes, of two inches focal distance, being free to expand from, and contract towards, the central microscope, independently of each other; and thereby forming with it small angles of inclination similar to the steel tongues of the compensation bars. The compensated point of each is so adjusted as to be in the outer focus of its object glass. The microscopes revolve on the axis of the telescopic microscope in a tube fastened to a horizontal plate attached to a tripod-stand with levelling screws, and furnished with longitudinal and lateral adjusting screws. On one side, secured to the brass bar, is the spirit-level, for levelling the microscopes, and on the other, firmly fixed to the centres of the bars by a brass plate, is a telescope, embraced by a brass collar, with a small cylinder projecting from one side, which turns in a socket attached to the plate; thus affording it a vertical motion, allowing With these arrangements the surgeon can never be objects to be seen in opposite directions. The telescopic taken by surprise, and is consequently always in a conmicroscope is provided with an adjusting screw, for alter-dition to remedy the effects of wounds and other acciing the focal distance within certain limits, as well as moveable object glasses of different focal lengths fitting into the lower end of the tube. The compensation microscopes are seven in number, the weight of each being 7 lbs.

[All the methods adopted in the measurement of base lines in trigonometrical surveys which had been in use previous to the survey of Ireland, depended more or less for their accuracy on the knowledge of the temperature of the bars, &c., used in measuring; but as the time which substances occupy in heating or cooling is dependent upon their nature, mass, &c., it did not appear that any application of thermometers would give the true temperature of a bar throughout its whole length, particularly when the temperature of the air itself was undergoing constant change.

be found.

dents.

7 HUTTON, JOHN, 9 Lucas Place, Commercial Road East -Inventor and Manufacturer.

Lady's gold watch, with patent single compensation stud. Gold watch, and silver lever and silver huntingwatches, with the same improvement.

Clock, with patent compensation pendulum and barofrom the changes in the density of the atmosphere. metric contrivance, to prevent the variation of rate arising

Marine chronometer, with patent pneumatic auxiliary compensation, for obviating errors in extremes of temperatures; this is effected by means of a metallic thermometer, which varies the air space in which the balance oscillates.

chronometer).
Gold first class watch (called Hutton's patent lever

Patent lever escapement, showing the parts separately.
Silver pocket chronometer, with improved adjustments.
Gold first class watch, with patent escapement and
spiral spring.

Gold watch, with patent double compensation spring, stud and patent escapement; adapted for riding, &c.

This circumstance led to the application of the principle of compensation used in gridiron pendulums, to devising an apparatus for measuring a base line. As metals have different capacities for heat, and their surfaces have different powers of radiation, experiments were made to equalize the effects of varying temperature in the brass and iron bars; and for this purpose the brass 8 bars were bronzed and varnished, and the iron bars were browned, lacquered, and smoked, and the amount of lamp-black so produced was gradually removed, on successive experiments, till the desired effect was obtained. -J. G.]

6

VEITCH, JAMES, 6 Ovington Square, Brompton-
Inventor.

An invention denominated the medico-chirurgical ambulance, for surgical use on the field of battle, with an operating table attached thereto. The solid structure is 3 feet 4 inches in length, 2 feet in breadth, to which there is affixed an inclined plane to raise the shoulders when required. The flap is 2 feet 6 inches in length, and of the same breadth as the solid structure, and is supported when necessary by a moveable beam that can be promptly projected from

CRAGG, JOHN, 8 Northampton Square, Clerkenwell

-Manufacturer. Varieties of gold and silver watches, and a model of lever movement.

9 YATES, THOMAS, Preston-Inventor, Patentee, and Manufacturer.

Patent clock, on the detached dead-beat principle. The wheel-work is so arranged that each vibration of the balance measures half a second, while in the ordinary detached lever each vibration measures a quarter of a second. The teeth of the escape-wheel are not so much undercut as in the ordinary lever. The pallets from the point of rest are drawn a complete circle to the escapewheel teeth; so that when the balance returns and unlocks the escapement, there is no recoil. This escapement will carry a heavier balance with less motive power, and consequently will require a stronger balance-spring. Gold watch, beating dead half seconds.

NORTH, NORTH CENTRAL, AND SOUTH CENTRAL GALLERIES.