Leslie&rsquos Hygrometer
This instrument consists of a glass syphon tube, terminated with a bulb or ball at each end, turned outwards from each other, as in fig. 76. The tube is partly filled with concentrated sulphuric acid, tinged by carmine. One of the balls is covered smoothly with fine muslin, and is kept continually moistened with pure water, drawn from a vase placed near it by the capillary attraction of a few strands of clean cotton-wick. The descent of the coloured liquid in the other stem will mark the
“Should the water become frozen on the ball, this hygrometer will still act; for evaporation goes on from the surface of ice in proportion to the dryness of the air. Leslie estimates, that when the ball is moist, air, at the temperature of the ball, will take up moisture equal to the sixteen-thousandth part of its weight, for each degree of his hygrometer; and as ice in melting requires one-seventh of the caloric consumed in converting water into vapour, when the ball is frozen, the hygrometer will sink more than when wet by 1° in 7°; and hence, in the frozen state, we must increase the value of the degrees one-seventh: so that each of them will correspond to an absorption of moisture equal to one-fourteen-thousandth part of the weight of the air.
“When this hygrometer stands at 15°, the air feels damp; from 30° to 40°, we reckon it dry; from 50° to 60°, very dry; and from 70° upwards, we should call it intensely dry. A room would feel uncomfortable, and would probably be unwholesome, if the instrument in it did not reach 30°. 15°; in summer often from 15° to 55°; and sometimes attains 80° or 90°. The greatest degree of dryness ever noticed by Leslie was at Paris, in the month of September, when the hygrometer indicated 120°.”—Professor Trail, in “Library of Useful Knowledge.”
In estimating the value of the indications of this hygrometer, it should be borne in mind that the scale adopted by Leslie was millesimal, that is to say, from the freezing to the boiling-point of water was divided into a thousand parts; ten millesimal degrees are therefore equal to one of the scale of Celsius.
More
-
Watch Aneroid
Subsequently the aneroid has been further reduced in size and it can now be had from an inch and a quarter to six inches in diameter. The smallest size can be enclosed in watch cases, fig. 35, or otherwise, so as to be adapted to the pocket. By a be... 2 Construction Of Barometers
In order that the instrument may be portable, it must be made a fixture and mounted on a support; and, further, to render it scientifically or even practically useful, many precautions are required in its construction. The following remarks apply to ... Admiral Fitzroy&rsquos Rain-gauge
A form of rain-gauge, very well adapted for expeditious observation at any time, has been designed by Admiral FitzRoy, and extensively employed by his observers. It is cylindrical in shape, with the funnel let into the top; and the rainfall is coll... Admiral Fitzroy&rsquos Scale Words
The directions given on the scales of these barometers were drawn up by Admiral FitzRoy, F.R.S. They appear to be founded on the following considerations:—</p> <p>Supposing a compass diagram, with the principal points laid down, the N.E. is ... Admiral Fitzroy&rsquos Words For The Scale
The graduation of inches and decimals are placed in this barometer on the right-hand side of the tube; and on a similar piece of porcelain, on the left-hand, are engraved, as legibly as they are expressed succinctly, the following words, of univers... Aneroids
<p>The beautiful and highly ingenious instrument called by the name <em>Aneroid</em>, is no less remarkable for the scientific principles of its construction and action, than for the nicety of its mechanism. It is a substitute, and perhaps the best of ... Atmospheric Electroscope
<div>Fig. 90.<br> <img src="/images/fig90.jpg" alt=""></div> <p><br> The simplest instrument for ascertaining at any time the electric condition of the atmosphere is an electroscope composed of two equal pieces of gold leaf, suspended from a brass... Barometer With Electrical Adjustment
<p>This barometer is useful to persons whose eyesight may be defective; and is capable of being read off to greater accuracy than ordinary barometers, as will be seen by the following description:—The barometer consists of an upright tube dippi... Baudin&rsquos Alcohol Minimum Thermometer
This instrument resembles Rutherford’s thermometer in appearance; its indications are given by the expansion and contraction of alcohol, and its minimum temperature is likewise registered by a glass index being pulled back and left behind by ... Beckley&rsquos Anemometer
Mr. R. Beckley, of the Kew Observatory, has devised a self-registering anemometer, which consists of three principal parts: Robinson’s cups for the determination of velocity; a double fan, or wind-mill governor, for obtaining the direction; an... Casella&rsquos Mercurial Minimum Thermometer
The general form and arrangement of this instrument is shown in fig. 60. A tube with large bore, <em>a</em>, has at the end a <em>flat glass diaphragm</em> formed by the abrupt junction of a small chamber, <em>b c</em>, the inlet to which at <em>b</... Causes Of Rain
When the invisible vapour which is diffused in the atmosphere becomes sufficiently cooled, it appears visible as mist or cloud, and a further reduction of temperature causes its precipitation as rain, hail, or snow. The cooling of the higher regions... Causes Which May Bring About A Fall Or A Rise In The Barometer
As heat produces rarefaction, a sudden rise of temperature in a distant quarter may affect the weight of the atmosphere over our heads, by producing an aerial current outwards, to supply the place of the lighter air which has moved from its former ... Chemical Weather Glass
This curious instrument appears to have been invented more than a hundred years ago, but the original maker is not known. It is simply a glass vial about ten inches long and three quarters of an inch in diameter, which is nearly filled, and hermetic... Daniel&rsquos Hygrometer
<div>Fig. 77.<br> <img src="/images/fig77.jpg" alt=""></div> <p>This instrument was invented about the year 1820, by Professor Daniel, the distinguished author of <em>Meteorological Essays</em>; and it entirely superseded all hygrometers depending ... Description Of The Thermometer
The ordinary thermometer consists of a glass tube of very fine bore, having a bulb of thin glass at one extremity, and closed at the other. The bulb and part of the tube contains mercury; the rest of the tube is a vacuum, and affords space for the ... Desirability Of Magnifying The Barometer Range
The limits within which the ordinary barometric column oscillates, do not exceed four inches for extreme range, while the ordinary range is confined to about two inches; hence it has often been felt that the public utility of the instrument would b... Dial Or Wheel Barometers
<p>The familiar household “Weather Glasses” are barometers on the syphon principle. The portions of the two limbs through which the mercury will rise and fall with the varying pressure of the atmosphere are made of precisely the same diame... Distribution And Effects Of Ozone
Mr. Glaisher has found that “the amount of ozone at stations of low elevation is small; at stations of high elevation, it is almost always present; and at other and intermediate stations, it is generally so. The presence and amount of ozone wo... Earth Thermometer
<p>The Earth Thermometer is for ascertaining the temperature of the soil at various depths. It is protected by a brass frame, pointed and strengthened at the end to facilitate insertion into the ground, as in fig. 51.</p> <div>Fig. 51.<br> <img src... Ebullition
The temperature at which a fluid <em>boils</em> is called the <em>boiling-point</em> of that particular fluid. It is different for different liquids; and, moreover, in the same liquid it varies with certain changes of circumstance. Thus the same liqu... Fishery Or Sea-coast Barometers
<div>Fig. 12.<br> <img src="/images/fig12.jpg" alt=""></div> <p><br> Fig. 12 gives a representation of these coast and fishery barometers. The frame is of solid oak, firmly screwed together. The scales are very legibly engraved on porcelain by Ne... Fortin&rsquos Barometer
Fortin’s plan of constructing a barometer cistern is shown in fig. 2. The cistern is formed of a glass cylinder, which allows of the level of the mercury within being seen. The bottom of the cylinder is made of sheep-skin or leather, like a ba... French Sea-coast Barometer
The French have imitated this form of barometer for coast service, and have translated Admiral FitzRoy’s indications for the scale as follows:—</p> <table summary="table" border="0" cellpadding="0" cellspacing="5"> <tbody> <tr> ... Fundamental Facts Regarding Atmospheric Electricity
The <em>general</em> electrical condition of the atmosphere is <em>positive</em> in relation to the surface of the earth and ocean, becoming more and more positive as the altitude increases. When the sky is overcast, and the clouds are moving in dif... Horticultural Minimum Thermometer
This instrument, represented in fig. 56, is a special construction of Rutherford’s minimum thermometer to meet the requirements of horticulturists. It is desirable, if not essential, that gardeners should have the means of ascertaining to what... Howard&rsquos Rain-gauge
It consists of a copper funnel, a stout glass or stone bottle, and a measuring glass. The bottle is to be placed upon the ground, with the funnel resting on its neck. A brass band or cylinder fixed upon the outer surface of the funnel envelops the n... Howson&rsquos Long Range Barometer
<div>Fig. 31.<br> <img src="/images/fig31.jpg" alt=""></div> <p><br> Very recently quite a novel design has been patented by Mr. Howson, for a long range barometer. The construction requires neither distortion of the tube, nor mechanism for conver... Hydrometer
<div>Fig. 96.<br> <img src="/images/fig96.jpg" alt=""></div> <div>Fig. 97.<br> <img src="/images/fig97.jpg" alt=""></div> <p><br> <p>A simple kind of hydrometer is very much used at sea, as “a sea-water test;” and as the observati... Hygrometric Substances
The instruments devised for the purpose of ascertaining the humidity of the atmosphere are termed <em>hygrometers</em>. The earliest invented hygrometers were constructed of substances readily acted upon by the vapour in the air, such as hair, grass... Importance Of Self-registering Thermometers
Heat being apparently the most effective agent in producing meteorological phenomena, the determination of the highest temperature of the day, and the lowest during the night, is a prime essential to enable an estimate of the climate of any place t... Instructions For The Sea-coast Barometer
The directions for fixing the barometer, and making it portable when it has to be removed, should be attended to carefully. The barometer should be suspended against a frame or piece of wood, so that light may be seen <em>through</em> the tube. Othe... Johnson&rsquos Metallic Deep-sea Thermometer
The objection to the employment of mercurial thermometers for ascertaining the temperature of the ocean at depths, arising from the compression of the bulbs, which was of such serious consequence previous to the modification made in the constructio... King&rsquos Self-registering Barometer
<div>Fig. 27.<br> <img src="/images/fig27.jpg" alt=""></div> <p><br> Mr. Alfred King, Engineer of the Liverpool Gas-light Company, designed, so long ago as 1854, a barometer to register, by a continuous pencil-tracing, the variations in the weight... Laws Of Rain-fall
Tropical countries have a dry and a wet season during the year: <em>dry</em>, when the sun is at the opposite side of the equator; <em>wet</em>, when the sun is overhead. With reference to the British Isles, the statistics collected by Mr. G. J. Sym... Leslie&rsquos Differential Thermometer
<div>Fig. 93.<br> <img src="/images/fig93.jpg" alt=""></div> <p><br> A glass tube having a large bulb at each extremity, and bent twice at right angles, as represented in figure 93, containing strong sulphuric acid tinged with carmine, and suppor... Leslie&rsquos Hygrometer
This instrument consists of a glass syphon tube, terminated with a bulb or ball at each end, turned outwards from each other, as in fig. 76. The tube is partly filled with concentrated sulphuric acid, tinged by carmine. One of the balls is covered s... Lightning Conductors
;The line of danger, whether from the burning or lifting power of lightning, is the line of strong and obstructed currents of air, of the greatest aerial friction.” Trees, church spires, wind-mills and other tall structures, obstruct the aeria... Marine Thermometer
<div>Fig. 52.<br> <img src="/images/fig52.jpg" alt=""></div> <p>This instrument is a special construction to meet the requirements of navigation. It consists of a carefully constructed thermometer divided on its stem to degrees, which are sufficien... Mason&rsquos Hygrometer
<p><br> <strong>The Dry and Wet Bulb Hygrometer, or Psychrometer</strong>, known also as Mason’s hygrometer (fig. 79), consists of two parallel thermometers, as nearly identical as possible, mounted on a wooden bracket, one marked <em>dry</em>... Maxima And Minima Thermometers
<p><br> <strong>80. Rutherford’s</strong> arrangement for obtaining a complete instrument for the registration of heat and cold was simply mounting a maximum thermometer and a minimum thermometer upon the same frame or slab. Thus constructed, ... Maxima Thermometers
<p><br> <strong>70. Rutherford’s Maximum Thermometer.</strong>—The maximum thermometer, invented by Dr. John Rutherford, differs from an ordinary thermometer in having a small cylinder of steel, porcelain, or aluminium, moving freely in... Mcneild&rsquos Long Range Barometer
A barometer designed by a gentleman named McNeild is on a directly opposite principle to the one just described. The tube is made to float on the mercury in the cistern. It is filled with mercury, inverted in the usual manner, then allowed to float,... Measurement Of Heights By The Aneroid
For measuring heights not exceeding many hundred feet above the sea-level by means of the aneroid, the following simple method will suffice:—</p> <p>Divide the difference between the aneroid readings at the lower and upper stations by ·00... Mercurial Minima Thermometers Desirable
Alcohol does not expand equally for equal increments of heat, consequently errors are likely to exist in the scale indications unless the graduations are very accurately—not necessarily equally—made. On this account, as well as from t... Metallic Barometer
<p>This instrument, the invention of M. Bourdon, has a great resemblance to the aneroid, but is much simpler in arrangement. The inventor has applied the same principle to the construction of metallic steam-pressure gauges. We are here, however, only ... Method Of Calculating Heights By The Barometer
The pressure of the atmosphere being measured by the barometer, it is evident that as the instrument is carried up a high mountain or elevated in a balloon, the length of the column must decrease as the atmospheric pressure decreases, in consequenc... Method Of Calculating Heights From Observations With The Mountain Thermometer
Having considered how to make observations with the proper care and accuracy, it becomes necessary to know how to deduce the height by calculation. That a constant intimate relation exists between the boiling temperature of water and the pressure of... Method Of Verifying Marine And Other Barometers
“In nearly all the barometers which had been employed at sea till recently the index correction varied through the range of scale readings, in proportion to the difference of capacity between the cistern and the tube. To find the index correc... Methods Of Ascertaining The Exact Boiling Temperature
The normal boiling temperature of water all nations have tacitly agreed to fix under a normal barometric pressure of 29·922 inches of mercury, having the temperature of melting ice, in the latitude of 45°, and at the sea-level. If the atmosph... Milne&rsquos Self-registering Barometer
For a long time a good and accurate self-recording barometer was much desired. This want is now satisfactorily supplied, not by one, but by several descriptions of apparatus. The one first to be described was the design of Admiral Sir A. Milne, who h... Minima Thermometers
<p><br> <strong>73. Rutherford’s Alcohol Minimum Thermometer</strong>, fig. 55, consists of a glass tube, the bulb and part of the bore of which is filled with perfectly pure spirits of wine, in which moves freely a black glass index. A slight... Modification Of Milne&rsquos Barometer
The great difficulty to be overcome in Milne’s barometer, is to adjust the mechanism for obtaining registration so that the action of the striker upon the pointer should not in the slightest degree dot upon the paper. The same clock gives rot... Mountain Barometer On Fortin&rsquos Principle
This barometer, with Fortin’s cistern, as arranged by Messrs. Negretti and Zambra, is an elegant, manageable, and very accurate instrument for travelling purposes, and well adapted for careful measurement of heights. The cistern is made large... Mountain Thermometer Sometimes Called Hypsometric Apparatus
We have now to examine the construction of the boiling-point thermometer, and its necessary appendages, as adapted for the determination of heights.</p> <div>Fig. 72.<br> <img src="/images/fig72.jpg" alt=""></div> <div>Fig. 73.<br> <img src="... Nature Of Ozone
During the action of a powerful electric machine, and in the decomposition of water by the voltaic battery, a peculiar odour is perceptible, which is considered to arise from the generation of a substance to which the term ozone has been given, on a... Negretti & Zambra&rsquos Second Patent Mercurial Minimum Thermometer
In this thermometer a principle is used that has been long known to scientific men, viz. the affinity of mercury for platinum. If mercury be placed in contact with platinum under ordinary circumstances, no effect will take place; but if the mercury... Negretti And Zambra&rsquos Farmer&rsquos Barometer And Domestic Weather-glass
<p>It is a well-known fact that the barometer is as much, or even more affected by a change of wind as it is by rain; and the objection raised against a simple barometer reading, as leaving the observer in doubt whether to expect wind or rain, is remo... Negretti And Zambra&rsquos Patent Maximum Thermometer
consists of a glass tube containing mercury fitted on an engraved scale, as shown in fig. 54. The part of the thermometer tube above the mercury is entirely free from air; and at the point A in the bend above the bulb, is inserted and fixed with th... Newman&rsquos Mountain Barometer
<div>Fig. 29.<br> <img src="/images/fig29.jpg" alt=""></div> <p><br> Fig. 29 is an illustration of the mountain barometer known as Newman’s. The cistern consists of two separate compartments;—the top of the lower and the bottom of the... On Sixe&rsquos Principle
Thermometers for ascertaining the temperature of the sea at various depths are constructed to register either the maximum or minimum temperature, or both. The principle of each instrument is that of Sixe. There are very few parts of the ocean in whi... Osler&rsquos Anemometer And Pluviometer
Mr. Follet Osler is the inventor of a self-recording apparatus which registers the direction and pressure of the wind, and the amount and duration of rain, upon the same sheet of paper. His apparatus has met with very much approbation, and has been... Phillip&rsquos Maximum Thermometer
A maximum thermometer, better perhaps in its action than Rutherford’s, has been suggested by Professor John Phillips, of Oxford. A small portion of air is introduced into an ordinary thermometer, so as to cut off about half an inch of the merc... Position For Rain-gauge &c
Rain gauges should be placed on the ground, in any position exposed to a free fall of rain, snow, or hail, where neither walls, buildings, nor trees shelter or cause eddies of wind. They should be supported by a frame, or other means, to prevent the... Pouillet&rsquos Pyrheliometer
<div>Fig. 67.<br> <img src="/images/fig67.jpg" alt=""></div> <p><br> This instrument is composed of a shallow cylinder of steel, <em>A</em>, fig. 67, which is filled with mercury. Into the cylinder a thermometer, <em>D</em>, is introduced, the ste... Precautions To Ensure Correct Graduation
Those who possess a boiling-point thermometer should satisfy themselves that it has been correctly graduated. To do this, it is advisable to verify it with the reading of a standard barometer reduced to 32° F. The table of “Vapour Tension&... Principle Of
If some mercury, or any other fluid, be poured into a tube of glass, bent in the form of <strong>∪</strong>, and open at both ends, it will rise to the same height in both limbs, the tube being held vertically. If mercury be poured in first, an... Principle Of The Barometer
<div>Fig. 1.<br> <img src="/images/fig1.jpg" alt=""></div> <p><br> The first instrument which gave the exact measure of the pressure of the atmosphere was invented by Torricelli, in 1643. It is constructed as follows:—A glass tube, CD (fig.... Regnault&rsquos Condenser Hygrometer
<div>Fig. 78.<br> <img src="/images/fig78.jpg" alt=""></div> <p><br> <p>(Fig. 78) consists of a tube, <em>C</em>, made of silver, very thin, and perfectly polished; the tube is larger at one end than the other, the large part being 1·8 inches i... Robinson&rsquos Anemometer
<em>Dr. Robinson</em>, of Armagh, is the inventor of a very successful anemometer, which determines the horizontal velocity of the wind. It was first used in 1850, in the meteorological and tidal observations made on the coast of Ireland under the d... Rules For Foretelling The Weather
<p><br> A RISING BAROMETER.</p> <div> <p>A “Rapid” rise indicates unsettled weather.</p> <p>A “Gradual” rise indicates settled weather.</p> <p>A “Rise,” with dry air, and cold increasing in summer, indicat... Self-compensating Standard Barometer
<p>This barometer has been suggested to Messrs. Negretti and Zambra by Wentworth Erk, Esq. It consists of a regular barometer; but attached to the vernier is a double rack worked with one pinion, so that in setting or adjusting the vernier in one posi...