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 rotation to the hollow wooden cylinder, D, upon which is mounted the registering paper. The clock must be rewound when a fresh paper is attached to the cylinder, which may be daily, weekly, or monthly, according to construction; and the series of dots impressed upon the paper shows the height of the barometric column every hour by day and night. The space traversed by the marker is precisely equal to the range of the barometric column.
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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...