^ in »dom."

AND SURGICAL INSTRUMENTS.

Nouth, Nouth Central, and South Central Gai.leiues.

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tri c , lsc ’ an, l remains perfectly quiet until the next elec-xvitjj approaches. If, in the interim, a cloud chargedof ti, la J? °“ly should descend or pass over, no movement■jJJ e disc takes place.

is a * e Pluviometer, or that part of the apparatus whichis f or ail ^, e d for registering the quantity of rain that fallsob Se , aiea *n the following manner:—On the top of thefr 0lu ''nt°ry there is a receiver of one foot square, clearthe (V., surrounding matter that might interfere with-!' ect fall of the rain upon its surface. From thisiusiq er a pipe conducts the rain into another receiverapp a fne observatory, directly under the registeringSet of • s ! i’ 1 th's ti lere ' s an air-float, connected with aOti e i '! lc iined planes, each inclined plane being equal to!llf )vei' °.^ ra in. These inclined planes, as they pass up,Paper . e indicator across the destined proportion of thetoV, Showin S> as it proceeds, the result of each droptin u P hundredth part of an inch in superficies, and con-i"sta* S )f° a d y ance until it arrives at one inch. It is thenScale v discharged, and returns to the zero of thetecei’ 01 ?°mmencement of another inch. The internalIdanp 61 ' ’ s calculated to contain six inches of rain, a? lat se ld om falls in this island during onepp l_ The register will show when it is nearly full.ii) Co e ’ w ater can then be drawn off without the slightestthe k “hence, and the float be re-adjusted to the zero ofinch.

Whi c i e . eva porator, 10, is an open cube of one foot square,is Co ls supplied with water from the larger vessel, andv essei Uecte d with the cube by a pipe underneath the twoCv ap s ’ 10-10. From that connexion the indicator of,V,! s t lati °n is carried to the marker or arm, 6, of theSiu-f a erin S paper, and is supported by a float from theeva Por t ? le water in the larger vessel. The cube orSugjp- ator is covered by a plate of glass at an angle ofb ut unj 11 delation to prevent rain from falling into it,file Su „ so close as to resist the air from freely acting uponit iria v )f C,J °f the water. When the water is exhausted,The be le ^ded from the pump in the observatory,'‘'’latii, *' 0 "' 01 ' or force of the wind is registered by a com-Plaue s U sus pended weights, acted upon by inclinedin connexion with a board of one footPosit* t0 rece ^ v e the impression; this board is kept in op-Us 1Tl . to the direction of the wind by a powerful vane,Part t) a - 0n keing as free from friction as possible, eveijeill 8 correctly counterpoised. When the board isby a by the wind, it raises the suspended weights

of the ^ P ass * n g over a pulley in a line with the directionwind, and well secured from the weather. The

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Carry ,7®^ ’weights in connexion with an inclined lever8iste r T Pencil of indication along the scale, which re-s cal e jj lil . e weight lifted in ozs. and lbs. avoirdupois ; thee qu a i a ^g been found, by repeated trials, to be correctly■ The (p 6 ^ e ‘Sbts recorded upon it.t'Uie by lrect l° n of the wind is also registered at the samePaper Aether pencil, which marks the course upon theP r °PoM- rou ghout the whole circle of the horizon, or thatrtl °n throno-u ™ll.l

tor jp n through which it passes.

‘he p ap e convenience of placing upon theam- to be registered, there is a roller, wi

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f ?hed f. ea< T to keep it from being deranged as it is unPlots’. °\ which proper receptacles are provided for the;p' e - Qerneat h the frame, and parallel to the rollers

ettt represents one day’s work of this instrument.

instrument'egistered, there is a roller, with a flange

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I The end of the paper is carried from this roller over theone above, at the north end of the frame, and conductedunder the indicators, and over the platform to the drivingand pressing rollers; it is then to be drawn forward untilit reaches a similar roller to that on which it was firstrolled, also underneath the frame; to this roller it is thento be fastened by springs prepared for that purpose. Thisroller has attached to one of its pivots a worm, upon whicha weight is wound up; which weight is equal to the powerrequisite to wind up the paper as it comes from the drivingroller, leaving a space between them, which gives theobserver an opportunity of seeing what has been registeredduring the last twenty-four hours.

For the purpose of reading off the register when removedfrom the apparatus, there are a set of scales in com-bination, corresponding correctly with those upon theinstrument.

The whole may be placed in a room six feet square,having an opening to the north for the convenience ofplacing the thermometer out of the range of the sun’srays, and the better for the action of the hygrometer.For the convenience of the lightning conductor and vane,an upper room would be preferable.

References to Plate 95.—1. Barometer. 2. Thermometer.3. Hygrometer. 4. Electrometer. 5. Pluviometer. 6.Evaporator. 7. Force of the wind. 8. Direction of thewind. 9. The Clock. 10. Receivers for Pluviometer andEvaporator.

Lawson's meteorological thermometer stand: this ap-paratus consists of a frame (fig. 1) of white deal hoards,and can be formed or constructed by any carpenter. Itis represented in the cut. It is made of an oblong trunk,T, 12 inches by 8 inches outside measure; to the oppositesides of which are nailed boards, b, b, at the distance ofthree-quarters of an inch, and projecting about six inchesfrom it towards the north. Outside of these are nailedother thin boards, c, c, full half an inch distant, and pro-jecting about four inches beyond the last-mentionedboards, also towards the north. These sides or shadesprevent the sun from heating the interior of the standwhere the thermometers are placed. The top, or pentboard, P, is made double, and the boards are placed atfull three-quarters of an inch distant from each other,and come forward so as to overhang, by a full inch, thenight index thermometer, placed immediately beneath,for the purpose of preventing rain or dew from fallingperpendicularly upon the bulb of the thermometer. Thelegs, L, L, of the stand are merely the continuation ofthe sides of the trunk. The board, F, F, is loaded, or thefeet fixed to the ground, to sustain the force of the wind.The interior. T, is blackened to prevent strong reflectionsof light.

The whole is to be painted white, and no other colour;except the face of the trunk, which may be black, to pre-vent strong reflections of light.

Fig. 4 is a ground plan, or bird’s-eye view of the ma-chine, which will assist any intelligent workman in itsconstruction. The sides and wood-work generally are ofhalf-inch white deal. The distance between the sides ofthe trunk T (fig. 1), and the board, or inner side, *, s,(fig. 4) is three-quarters of an inch; and the distance fromthat board to the outer side, o, s (fig. 4), is full half aninch. The narrow boards, s, s (fig. 4), are to be nailed,with studs intervening, to the middle hoard or side, i, s ■and are designed to prevent the sun from shining betweenthe trunk and the sides, o, s, and i, s, when near the meri-dian. The sides are fixed, one upon the other, at therequired distance (viz., three-quarters of an inch, andhalf an inch), by numerous wooden studs, shown in figs.1, 2, and 3, about three-quarters of an inch diameter;the nails or screws passed through the sides and studs,fixing the whole firmly together. The whole is to hepainted white, except the face of the trunk T, which maybe black, to prevent strong reflection of light.

Fig. 2 is the view of the north side of the stand. No. 1is an index thermometer, to give the greatest heat of theair in the shade each day. No. 2 is an index spirit ther-mometer, to give the greatest cold of the night. No. 4