this country, although it possesses considerable advantages over drawing them on stone, or engraving them on metal.

712 CLAPHAM, John Kighley, 6 Briggate, Leeds

Proprietor.

A county map of the United States of America, from a steel plate, on Goodyear's gum elastic.

713 BROWN, JOSEPH, 71 Leadenhall Street-Inventor and Manufacturer.

Aërial machine.

714 MASON, EDWARD, Brompton Post Office-Inventor and Manufacturer.

A model of a navigable balloon, which works by sails, helm, and mariner's compass. Scale inch to a foot.

715 BELL, HгGн, Baltic Whorf, Millbank-Inventor and Manufacturer.

Model of a "locomotive balloon." The steering apparatus has the motions of a bird's tail; the car is so arranged with buoyant apparatus at the ends, as to be a life boat in case of a descent being made into the sea, and the balloon and machinery may be stowed away in it. Improved valve for a balloon.

Model arrangement for a "locomotive parachute," equipped for service.

716 PLUMMER, H. LORENZO, 112 Porris Street, Woolrich, Kent-Inventor.

Working model of an aerial machine, with wings, which is put in motion by a clock-spring.

717 WATT, G. T., 2 William Street, Albert Gate, Hyde Park -Inventor.

Dentistry: consisting of specimens of artificial palates, models of the mouth and jaw, and sets of teeth of various construction, of hippopotamus tusk, porcelain, &c.

718 DINSDALE, CUTHBERT, Newcastle-Manufacturer and

Inventor.

Model of artificial gums, composed of incorrodible material, showing a metallic artificial alveolar process. Patented in England, Scotland, and France. Wax models of the human head. Model of a dissected human head. Series of wax models, showing the different stages of incubation in the egg of the barn-door fowl.

[The mysterious changes which occur in the egg on the application of the stimulus of heat, and the progress of the germ up to its perfect condition, have long attracted the attention of physiologists.-R. E.]

719 ROSE, J. E., 68 Mount Pleasant, liverpolManufacturer.

Artificial teeth, with models of the mouth.

725 KENNEDY, EVORRY, M.D., Merrion Square, Dublin -Inventor.

Siphon, adapted to green-house or garden watering. The principle is the substitution of an elastic caoutchouc chamber, for the suction pump to procure exhaustion, the water being directed in its course by double ball and socket valves. The pressure of the hand or carriage handle expels the water, and its own elasticity procures the exhaustion. The siphon has a sustained or continuous action, by means of an external exhausted air-chamber.

Siphon adapted to medical purposes, as a substitute for the pumps at present in use for throwing fluids into internal cavities. The exhaustion is produced by the elasticity of the India-rubber bag itself, the fluid being propelled by the pressure of one hand leaving the other free to guide the instrument; the material is not acted upon by the usual chemical agents.

726 SELTZER, SOPH:A, 7 Upper Ronelagh Street, Pimlico-Inventor.

Chair for spinal curvature.

727 HIGHLEY, SAMUEL, 32 Fleet Street-Producer.

An anatomical statuette, height, 27 inches, exhibiting the external muscles of the human figure; carefully modelled, and expressly adapted for the use of artists, and others interested in the study of anatomy; accompanied by a key, containing outline views of the statuette in its several aspects, with references to the names of the muscles.

727A

TITTERTON-Inventor.

Instrument for slaughtering cattle.

728 LANAGAN, FRANCIS, 12 Brownlow Street, Bedford Row. Apparatus, and shoes for the cure of bunions.

729 EWART, George, 19 Quickset Row, New Road, Regent's I a k-Manufacturer.

Zinc spirometers, for ascertaining the capacity of the lungs; zinc mouldings for the decoration of buildings, internal and external; and samples of manufactured zinc.

[The spirometer is an instrument invented in order to determine the capacity of the human lungs. Its principle is extremely simple. It is merely an inverted zine cylinder, balanced by a weight, and rising and falling within another outer case containing water: it has, consequently, a close resemblance to a gas-holder. The extremity of a tube leading into the inner cylinder is applied to the mouth of the individual, who is directed to expel the air from the chest as far as it is possible to do so. The inner cylinder rises, carrying with it a measured scale, on which the cubic capacity of the lungs is easily read off. When this scale indicates an unusual departure from an ascertained average, disease is generally found to exist.-R. E.]

730 RITTERBRANDT, DR. L. A., 7 Northumberland Street, Strand Inventor.

Galvanic bath. The principle of this bath is simple; it consists of a vessel constructed of two different metals, separated by a non-metallic substance which not merely fulfils the purpose of an ordinary bath, but at the same time acts as a perfect battery.

The metals employed are zinc and copper, the latter being plated with silver. This combination, however, is not the only one that may be employed. Any other two

metals differing in their electrical relations-that is, positive and negative to each other-will afford in a more or less degree the same result; as, for example, zinc and iron, iron and copper, &c.

This bath is a simple apparatus for causing a current of electricity to pass through the body of the bather. The fluid employed is common water. By connecting the wires attached to the two metals a strong current of electricity will be made to pass through the body of the bather, which will be attested by the deflection of the needle of the galvanometer attached to the bath. If, instead of cold water, warm water be employed, the deflection of the needle will increase in proportion to the temperature of the water. If a small quantity of common salt, or any soluble salt be added, or sea or mineral spring water employed, the current of electricity will still further increase; notwithstanding which, however, it will pass so mildly and imperceptibly through the body as to obviate any unpleasant sensation.

În cases where it is necessary to make use of electricity of greater intensity than that producible by the bath, this may be effected by combining it with one or more cells of an ordinary battery, so as constitute one compound battery. Where it is necessary to pass shocks through the body of the patient it can be effected, in the bath, in several ways:-1. By closing two of the caps of a single coil with a wire, and connecting the other two by wires attached to the bath. 2. By connecting one or more cells of a battery with the caps of a primary coil, and connecting the two ends of the secondary coil with the wires of the bath; care being taken that the direction of the current from the coil coincides with that of the bath. 3. By using a single coil, connecting two of its caps with a battery, and the two others with the two wires of the bath--viz., the positive wire of the coil with the negative wire of the bath, or with the wire attached to the zinc, and vice versa. In this manner the patient will receive shocks from the electricity of the coil, while his body will be affected by the electricity from the bath.

732 BADCOCK, JOHN, Brighton-Producer.

Photographic specimens of vaccine, produced by inoculating the cow with small-pox, showing the character of the vesicles in their different stages. The specimens, furnished by Mr. Constable of Brighton, show the genuine vaccine vesicle and its characteristic areola as described by Dr. Jenner.

[The production of vaccine virus is a subject of much importance. The exhibitor states that he has proved the efficiency of virus thus obtained, and suggests that by proceeding in the manner described, a supply of virus may be procured without the loss of time caused by sending, in some instances, many thousand miles for vaccine.-R. E.]

733 HAMILTON, HENRY G., R.N. 71 Eccleston Square— Producer.

Collection of ancient Greek coins electrotyped by the exhibitor.

734 BLACKWELL, WM., 3 Bedford Court, Covent GardenInventor.

Apparatus for fractures, trusses, and surgical instru

ments.

735 BRYCESON, HENRY, 5 Tottenham Court New Road, St. Pancras-Manufacturer.

741

SIMMS, WILLIAM (surviving partner in the firm of TROUGHTON and SIMMS), 138, Fleet Street— Inventor and Manufacturer.

An equatorial instrument, adapted for the latitude of 25°, and mounted generally after the method of Frauenhofer; it is furnished with a clock-work motion, so that the telescope moves so as to counteract the effect of the earth's rotation; the diameter of the object-glass is four inches and nine-tenths of an inch, and its focal length is about 7 feet.

The declination axis is open and exposed between its two supports; its ends are cylindrical, and admit of the application of a spirit-level, by this means the adjustment of the instrument is facilitated, and it is readily brought to the meridian, and thus, observations of transits over the meridian can be made sufficiently near for identifying an object.

The illumination of the telescope is regulated by the application of the throttle valve of a steam-engine, and is as effective as the more elaborate methods hitherto in use.

A best spider line position micrometer, of which extensive use has been made in measurements of the relative position and distance of binary stars. The position circle is divided to one minute of arc, and the reading is by means of opposite verniers upon the edge of the circular plate to which the micrometer is fixed; the value of the micrometrical divisions, however, depend on the focal length of the telescope with which this instrument is employed. An annular micrometer, and a set of negative eye-pieces are shown with this instrument.

An equatorial instrument adapted for the latitude of London, on the same principle as the preceding, but without clock motion. It has been arranged as an inexpensive, but at the same time an effective instrument. The diameter of the object-glass is 34 inches, and its focal length is about 45 inches; it is provided with a spider line position micrometer of the second order, in which one screw motion only is given.

The whole is supported upon an iron column with suitable arrangements for its final adjustments.

[An equatorial instrument consists of a telescope fixed to a graduated circle called the declination circle, and of a polar axis, to which is fixed a circle called the hour circle. When the instrument is adjusted the polar axis is parallel to the axis of the earth, and perpendicular to the plane of the hour circle, and to the axis of the declination circle, &c. In its use, the delination circle can be turned about the polar axis, and the telescope can be directed so as to be inclined at all angles to the earth's axis, and by the means of these two motions, the telescope can be directed to any point in the heavens, and if a clock-work motion be applied, an object when viewed through the telescope seems to be without motion, affording the opportunity of examining it minutely.-J. G.]

The altitude and azimuth instrument, known as the "Westbury Circle," so called from the valuable observations made with it at Westbury by John Pond, Esq., the late Astronomer Royal, by which a change of figure in the great mural quadrant at the Royal Observatory was clearly demonstrated.

This instrument was made originally by the late E.

736 GOWING, J. W., Camden Town-Inventor.

Instruments for operating on the teeth of horses. Apparatus for fractures, &c. Neurotomy knife, and

scissors for dividing nerves.

737 WOOD, J. W., Manchester-Inventor.

the exhibitor. The re-division was effected by the process invented by Troughton, and described by him in the Philosophical Transactions for 1809.

The diameter of the altitude circle is 30 inches, and of the azimuth 24 inches. The spaces upon the respective circles measure five minutes of arc, which are subdivided to single seconds by two opposite micrometer microscopes. Five revolutions of the micrometer screw being, by the arc upon the circle; the 60th part of a revolution of the

[10.]

2 N-P

micrometer screw is, therefore, equal to one second of are. The positions of the azimuthal micrometers are unalterable; those of the altitude circle are fixed to the extremities of an arm which is moveable upon a centre, an arrangement which admits of their positions being altered relatively to the zero of the circle, and hence the readings obtained upon particular objects are changed in every new series of observations. Such errors as are due to the graduation are by these means much diminished if not entirely eliminated. The axes are adjusted by means of spirit-levels, in addition to which the instrument is furnished with a plumb-line apparatus.

A portable altitude and azimuth instrument: each circle is 15 inches in diameter, graduated upon bands of silver to five minutes of arc, upon Mr. Simms' new self-acting dividing engine. There are two micrometer microscopes to each circle showing single seconds of arc. The microscopes have achromatic object-glasses. This instrument is furnished with the nadir point apparatus, or central collimator, the invention of the exhibitor, which consists of a telescope in the interior azimuthal axis, around which the superior parts of the instrument revolve. The spider lines, in the form of an acute cross upon the diaphragm of this central collimator, being placed in the principal forms of its object-glass, can be seen in the telescope of the instrument when it is directed downwards, or towards the Nadir; and their intersecting point serves as an object to which every observation made with the instrument can be referred, and therefore supersedes the use of an artificial horizon, or other extraneous means having the same object in view. The transit collimation can also be adjusted by its means, without reference to any external object, and it supplies the place of the riding level for the transit axis, in the event of its being broken.

A transit circle, 2 feet diameter, with two reading micrometer microscopes having achromatic object-glasses; the divisions upon the circle are sub-divided to single seconds by the micrometers. This circle was also graduated upon the self-acting dividing engine invented by the exhibitor, as were also the circles of the altazimuth and the transit circle lately made for the Royal Observatory at Greenwich.

The telescope is achromatic and has an aperture of 34 inches, and a focal length of about 46 inches. The apparatus by which the field of view is illuminated is the invention of the exhibitor, and has been adapted to the great transit circle at the Royal Observatory. The field of view and the wires interchange the conditions of light and darkness; hence, if the object be a bright one, the field of view can be illuminated, and the wires appear as dark lines upon it; but if the object be a faint one, the

better for its work. Firstly, a reversing frame by which the telescope can be lifted from the Y's, turned end for end and again lowered into its bearings without being subjected to any handling, or other operation by which the parts may be unequally expanded and the adjust ments deranged; the operation is safe and expeditious. Secondly, both the pivots are perforated, in one of which a diaphragm with cross lines and an eye piece is fitted, and in the other an object-glass of suitable focal length is fixed, and hence the axis becomes a telescope. Now, if this telescope be directed to any object, such as the cross lines of a collimator or any terrestrial mark that presents itself, or is set up at a considerable distance from the instrument, and the axis be made to revolve, the form of the pivots may be thereby examined, or (which in the instrument exhibited, is its primary purpose) this telescope may be used for turning the principal telescope 90°; that is to say, for changing its meridional to a prime vertical position, or the reverse.

This instrument is supported upon a cast-iron stand. in the meridian. It is fixed to two arms, the extremities [The transit instrument consists of a telescope placed of which are turned into two equal cylindrical pivots, which turn in Y's on the top of two piers, placed east and west of the centre of the telescope. The centres of the pivots, or their axes are in the same straight line, which is called the axis of the instrument. In order to observe the instant that a celestial object passes the meridian, there is placed in the telescope, at the focus of the object glass, a system of fine cobweb wires perpendicular to the horizon, and one placed horizontal. At the instant an intersection of these wires. An arrangement of this kind observation is made, the star's image coincides with the is absolutely necessary, as the field of view of the telescope is not a mere point.

The transit instrument is used in connexion with an astronomical clock, adjusted to sidereal time. A clock so adjusted that it completes a circuit in a sidereal day, and indicates Oh. Om. Os., when the first point of Aries is on the meridian, and having its dial-plate divided into 24 equal spaces; hence, when the transit instrument is adjusted, and the clock goes correctly, at the instant the first point of Aries is on the meridian, the time shown by the clock is Oh.; when this point is 15° or 30° west of the meridian, the time shown by the clock is 1h. or 2h. respectively, and so on.—J. G.]

The illumination of the divisions upon the circle is effected by the same lamp which illuminates the field of the telescope, as follows:

A prism adjoining the microscope object-glass receives the light from a lens in the side of the lantern, which is condensed upon the graduated face of the circle as a disc of light, which just covers the extent of the field of the micrometer microscope, and is so arranged that a normal to the face of the circle bisects the angle formed by the incident and reflected rays.

The instrument is supported upon wooden models of the stone piers upon which it will be ultimately fixed; and the whole may be taken as a representative of the class of instrument which is now rising in the estimation of British astronomers.

A transit instrument 34 feet focal length, and 23 inches aperture, with two setting circles upon the telescope tube, axis level, micrometer in the eye-piece, &c., as is usual in the most perfect instruments of this class; but as this instrument has been made for the coast survey of the United States, now being carried on under the direction of Professor Á. D. Bache, and is intended for observations both in the meridian and prime vertical, the exhibitor has introduced two additional parts to fit it the

strument, and is the invention of the exhibitor.

The mode hitherto adopted has been the placing of a reflecting surface in front of the object-glass, and receiving light upon this plate from a lamp or candle placed in a distant part of the observatory. The objections to this mode are, the difficulty of throwing light upon the reflector at all, under such circumstances; besides, for every observation, a new arrangement of the light has to be made; and further, by the reflector being placed in front of the object-glass, part of its light is cut off.

In the instrument exhibited, the light passes through the axis, and this is effected by placing a lens, of which a very large segment, nearly an annulus, projects beyond the edge of the diagonal reflector within the axis. The light, passing through a small lens fixed in one of the pivots in the usual way, diverges upon the open segment of the interior lens, and is thereby converged to the opposite pivot, where the diaphragm is placed.

An isometrical elliptograph invented by the Astronomer Royal, G. B. Airy, Esq., by which ellipses in isometrical perspective can be drawn with great facility and accuracy. The exhibitor is the manufacturer.

Three imperial standard yards, made for Her Majesty's Commissioners for the restoration of the Standard of Weights and Measures, with the supports invented by Professor Miller and the Rev. R. Sheepshanks.