Mercury Barometer Research Articles

LXXIX. The effect of the rolling of a ship on the readings of a marine mercury barometer

LXXIX. <i>The effect of the rolling of a ship on the readings of a marine mercury barometer</i>

A Simple Regenerative Vacuum Device and Some of its Applications

The Paper deals with the difficulties arising from residual traces of air fouling the vacuum above the mercury column in syphon gauges and other devices. A remedy is suggested in the form of a small attachment taking the shape of bent capillary tubing ending in a bulb. This enables the air to be repeatedly pushed into the vacuum of this bulb, the mercury at the bottom of the capillary preventing the subsequent return of the air. With such an arrangement fitted to the top of a syphon gauge the height of the column of mercury becomes a true measure of the gas pressure, subject only to the definite correction for the vapour pressure of mercury and temperature. The device is regenerative in the sense that, irrespective of any progressive fouling of the vacuum, a fresh air-free vacuum is automatically created by it every time it is brought into action. As typical examples of the wide field of utility of the device its application to mercury barometers and mercury vapour lamps is also briefly discussed.

An Inverted Siphon in a Suction Line

A feature of water works construction which presents elements of great concern to the designing engineer is the so-called suction line leading from the source of water supply to the pumping machinery. A statement of the natural phenomena responsible for the performance of liquids under these circumstances will be pertinent. When a piston traverses the course of its component cylinder, whatever substance occupies the body of the cylinder must needs be displaced, and as the channel provided for its movement is usually that circumscribed by the pipe leading from the cylinder, there is no limit to which the fluid may be forced other than that set by the strength of the pipe to withstand the pressure and the power supplied behind the piston to deliver it. On the other hand, in all cases where the pump cylinder is at a higher elevation than the source of supply, there is a determinate limit to which any liquid will rise to fill the space vacated by the piston in its forward movement. The temperature of the liquid in a measure affects the operation of pumps, but inasmuch as the cases occurring in water works operation have to do with water only, and at temperatures varying only from 33° to 70°, this feature may be neglected. The height to which water will rise to fill a chamber vacated by a piston is directly proportional to the pressure of the air, which in turn varies with the elevation of the station above sea level, being greatest at sea level and reducing gradually with the height. In terms most used by the engineer these relations are expressed in inches on the mercury barometer or in feet on the water barometer, a fixed ratio existing between the two. At sea level we have 30 inches mercury and 34 feet water pressure; at an elevation of 1000 feet, 28.94 inches mercury and 33.3 feet water; at 2000 feet elevation, 27.92 inches mercury and 31.6 feet water; at 10,000 feet ele-

Scientific Serials

American Meteorological Journal, May.—The principal article is “Meteorology and Geodesy,” by Prof. C. Abbe. It contains tables showing the variations in the force of gravity over the North American continent and the Atlantic ocean and their effect on the mercurial barometer. The author points out that there is a local attraction of gravitation that is less over the continents than over the oceans, and probably, on the average, less in the northern than in the southern atmosphere; these differences must be allowed for, in combination with the effects due to the density of the atmosphere and to centrifugal force. The principal lesistance to the motion of the atmosphere originates in the connective processes that force stagnant air to mix with air in motion; this convective friction is quite independent of viscosity, which has been generally introduced into the formulæ for atmospheric motion, and it is much more effective. The most important subject for the meteorologist to study is these convective mixtures and the resistances or accelerations that result therefrom. The author considers it unnecessary to take up the minute irregularities treated of in this paper, until after the study above referred to has explained the larger part of the irregularities of atmospheric motions. The same journal contains tome very useful suggestions by Prof. Abbe, on the various meteorological problems that might be taken up by mathematical students.

Scientific Serials

American Journal of Science, November 1891.—The solution of vulcanized india-rubber, by Carl Barus. Experiments have been made by the author on the solubility of india-rubber in different solvents at different temperatures. Elastic sheet india-rubber, such as is used for rubber bands and tubing, is not fully soluble in CS2 at 100° or 160°, but is quite soluble at 185°, and extremely soluble at 210°. It is also easily dissolved by liquids of the paraffin series at 200°. Various other substances have been used as solvents, and many remarkable results obtained. The importance of the paper may be gathered from the fact that in it is described “a method by which vulcanized india-rubber of any quality or character whatever, as well as the undecomposed or reclaimable part of rubber-waste, may be dissolved or liquefied in a reasonably short time, the solutions possessing any desirable degree of viscosity or diluteness, from which india-rubber may be regained on evaporation of the solvents.”—Report of the examination by means of the microscope of specimens of infusorial earths of the Pacific coast of the United States, by Dr. Arthur M. Edwards. Seven new fluviatile fossiliferous deposits from Oregon, California, and Washington are described.—The Tonganoxie meteorite, by E. H. S. Bailey. An analysis of the meteorite gave the percentage composition: Fe 91.18, Ni 7.93, Co 0.9, P 0.10, and a trace of copper. The weight is 23¼ 1bs., specific gravity 7.45, shape an irregular triangular pyramid 9½ inches long by 6½ inches wide by 4½ inches deep. A fine figure showing numerous pittings on the surface of the meteorite accompanies the paper.—Proposed form of mercurial barometer, by W. J. Waggener.—Colour photography by Lippmann's process, by Charles B. Thwing. The results obtained seem to indicate—(1) that mixed colours may be reproduced with a fair degree of accuracy; (2) that an exposure sufficiently long to give a clear image of the red is quite certain to obliterate the blue by over-exposure; and (3) that an over-exposure may completely reverse the colours, causing the original colours to appear on the reverse, and the complementary colours on the film side of the plate.—New analyses of uraninite, by W. F. Hillebrand. From the analyses it appears that the species may be broadly divided into two groups, one characterized by the presence of rare earths and the almost invariable presence of nitrogen, the other containing little or no nitrogen and no rare earths. Varieties of the former group occur in more or less well defined crystals, whilst members of the latter group are usually devoid of crystalline form.— The Tertiary silicified woods of Eastern Arkansas, by R. Ellsworth Call. The investigation has led to the following conclusions:—(1) The silicified woods of Eastern Arkansas are all of Tertiary age. (2) They are derived from the beds of Eocene clays that underlie the sands and gravels in which they commonly occur. (3) They are silicified lignite; the process of silicification has occurred either while they were still in clays, or most often after they were removed and buried in the sands or gravels. (4) They possess as yet no taxonomic value in determining the relative ages of the members of the Tertiary series.—Occurrence of sulphur, orpiment, axd realgar in the Yellowstone National Park, by Walter H. Weed and Louis V. Pirsson.—Mineralogical notes, by L. V. Pirsson. Some specimens of cerussite, hæmatite, and cassiterite, gypsum, and pennine are described.—Peridot dykes in the Portage sandstones, near Ithaca, N.Y., by J. F. Kemp.—A new locality of meteoric iron, with a preliminary notice of the discovery of diamonds in the iron, by A. E. Foote. The existence of black and white diamonds in the meteorite appears to be established by indifference to chemical agents and hardness. Carbon in the form of an iron carbide also occurs with the diamonds. The meteorite was found in Cañon Diablo, Arizona. Three figures accompany the paper.—The South Trap Range of the Keweenawan series, by M. E. Wadsworth.—Geological facts noted on Grand River, Labrador, by Austin Gary.

Proposed form of mercurial barometer

<h3>Objective:</h3> To present initial validity evidence for MyCog. <h3>Background:</h3> Cognitive Impairment (CI) affects more than 16 million people, with dementia or severe cognitive decline projected to increase significantly by 2050. MyCog is a brief, standardized iPad-based, self-administered cognitive screening assessment designed for use in diverse clinical settings, among older adults or any patient with a recognized cognitive concern. It will address the need for sensitive measures of CI feasible for use in primary care settings. <h3>Design/Methods:</h3> Participants were recruited from an ongoing cognitive aging study conducted in academic internal medicine clinic and community health centers. CI was determined based on either a chart diagnosis of dementia or mild cognitive impairment (MCI), or by normative performance on a comprehensive cognitive battery within the prior 18 months. The MyCog assessments, Dimensional Change Card Sort (DCCS) and Picture Sequence Memory (PSM), measure executive function, cognitive flexibility, and episodic memory. We evaluated the efficacy of MyCog as a detection tool using sensitivity, specificity, and receiver operator characteristic (ROC) curves. <h3>Results:</h3> Of the 80 participants administered the MyCog assessment, 31 were classified as CI. In the sub-sample of participants who expressed concern about their cognition (n = 52), PSM and DCCS demonstrated exceptional ability in detecting CI (the area under the ROC curve, or AUC, = 0.92), with an average administration time of 12 minutes. When only including the first of two PSM trials along with DCCS, time was reduced on an average to &lt;7 minutes, with little change in AUC (0.90). <h3>Conclusions:</h3> Preliminary validity evidence supports the use of MyCog as a self-administered cognitive screening battery. Given the COVID-19 pandemic, it is important to provide physicians and clinical staff access to well-designed cognitive assessments that can be self-administered. We are currently validating MyCog in MCI clinical populations, and our next steps include a clinical trial with modified clinic workflows. <b>Disclosure:</b> Zahra Hosseinian has nothing to disclose. The institution of Ms. M Curtis has received research support from NINDS. Dr. Shono has nothing to disclose. Saki Amagai has nothing to disclose. Ms. Benavente has received research support from National Institutes of Health. Mr. Bass has nothing to disclose. Maria Varela Diaz has nothing to disclose. Mrs. Batio has nothing to disclose. The institution of Dr. Nowinski has received research support from National Institutes of Health. The institution of Richard Gershon has received research support from National Institutes of Health (NIH). The institution of Richard Gershon has received research support from National Institute on Aging

Geographical Notes

GREAT activity is still being displayed by German explorers in the interior of Togo-land. Captain C. von François has brought to a successful termination his journey into the country confined within the great bend of the Niger. The route taken by him was as follows: viz. Kpandu, Salaga, Jendi, Gambaga, and then across the upper course of the Volta at Bupere (the river at this spot, though more than 80 yards broad, is no longer navigable). From this point he arrived on April 19 last at Surma (11° 28° N. lat.) in the country of Mosi. He afterwards made an excursion from Gambaga to the south-west by way of Nantong to the River Volta, and returned to the coast through Adeli. In the latter place he met Dr. L. Wolf, who founded a station there on the Adado Mountains in the beginning of May, having travelled to Adeli through the eastern part of Togo-land. Dr. Wolf has, with the aid of a mercurial barometer, been able to determine numerous altitudes with greater accuracy than any measurements previously made in this part of Africa. It appears from his results that Dr. Henrici has considerably over-estimated the height of the Agome Mountains. Herr von Puttkarner, the Imperial Commissioner, made in March an excursion into the region of the French Protectorate as far as the lower course of the Mono, and then explored the country of Agotime up to the foot of the mountains. All these travellers agree in stating that the prospects of the interior of Togo-land are very favourable, both as regards agriculture and commerce. The climatic conditions of these uplands are much more favourable than those of the coast.

Our Astronomical Column

CORRECTIONS TO REFRACTION TABLES.—Prof. Cleveland Abbe, in a short note to the Astronomische Nachrichten, calls attention to the fact that the reading of the mercurial barometer which is used in the refraction-formula as an index to the density of the air is not a true index to the pressure controlling that density until it is corrected for the effect of the variations in gravity. The correction is accomplished by adding one more factor, g; for gravity, when the formula becomes—

Geographical Notes

IN a lecture delivered at Cooktown (published in the Daily Observer of Brisbane), Mr. H. O. Forbes described his work in New Guinea during the six months he remained there. He set up his winter camp at Sogere, three days' march from the coast, though only 25 miles in a straight line, on the slope of a steep mountain. His work here was varied and important. The meteorological station which was erected was placed under the charge of Mr. Hennessy, and the observations were continued down to the end of his stay. These consisted of records of the mercurial barometer, maximum and minimum, dry- and wet-bulb thermometers, and rainfall, and were recorded without interruption six times in every twenty-four hours. The mass of observations thus accumulated will take a considerable time to tabulate, especially those referring to the atmospheric humidity. Then there was the collecting of zoological and botanical specimens. A large portion of the herbarium consists of giant trees of the forest. It contains about one thousand specimens, one set having been sent to Baron von Müller to Melbourne. A great part of Mr. Forbes's own time was devoted to the survey and delineation of the geographical features of the country. He obtained angles from about fifty different stations and established a base of several miles in length, on which he had hoped to found the triangulation of the country between Sogere and Owen Stanley, and the north-east coast. He also paid a visit to the latter place, and there, as elsewhere with a little management, found the natives extremely friendly and well-disposed. When Mr. Forbes found his funds failing, he determined, with Mr. Chalmers, on making a dash for Mount Owen Stanley, but the natives who were to have aided him fled in the night, apparently on account of the terrors inspired by the journey. He only got as far as Kaukari, a village two days' journey beyond Sogere. He says that no words can give a true idea of the break-neck, shattered, disrupted condition of the country between Sogere and the central ridges. Beyond the natural obstacles, however (and they appear to be very great), there appears no reason why British New Guinea should not be thoroughly explored, provided the natives are treated with conciliation and tact.

VI. Notes on the microscopic structure of some rocks from the andes of ecuador, collected by E. Whymper. No. III. Cotopaxi and Chimborazo

In regard to these two important volcanic mountains of the Ecuadorian Andes, Mr. Whymper has favoured mo with some descriptive notes, which appear to me of so much interest that I incorporate them with but slight modification into my paper. Cotopaxi. “Two volcanoes in Ecnador—Sangai and Cotopaxi—are always in a state of activity, and, of these two, the latter is the higher and the more important mountain. Cotopaxi, according to my observations with mercurial barometer on its summit, is 19,650 feet high, and it is the second in altitude of the Andes of Ecuador, being inferior only to Chimborazo.

Draper's Self-Recording, Mercurial Barometer

Draper's Self-Recording, Mercurial Barometer

Geographical Notes

MR. EDWARD WHYMPER on Monday last addressed a large meeting of the Geographical Society on some features in his recent journey among the Great Andes of the Equator. His paper was not, however, of so popular a nature as those which he read before the Alpine Club and the Society of Arts. The chief facts left on the minds of his very attentive audience may be briefly stated. Mr. Whymper found by careful experiments that aneroid barometers are not to be depended upon for the determination of heights, and that there is a remarkable difference in altitudes as fixed by the boiling point of water and the mercurial barometer. He asserted, as the result of his observations, that it is a mistake to suppose that there are two parallel chains in the Ecuadorian Andes, as usually shown on our maps. This is a point, however, on which more light is evidently required. Mr. Whymper's account of his ascent of the hitherto unknown peak called Sara-Urcu, was very interesting, and this achievement alone would stamp him a mountaineer of the highest skill and courage.

Geographical Notes

Geographical Notes

III. On the construction of a glycerine barometer

Various attempts have been made from time to time to construct barometers with fluids of lower density than mercury, with the view of increasing the range of movement of the column by the direct action of the atmosphere, thereby rendering the variations of pressure more easily visible, without the intervention of mechanical appliances. I have been induced to give the subject attention in the belief that if precise instruments of this class could be made they would prove of scientific value in showing the character of the more minute vibrations of atmospheric pressure, and of practical use at storm stations, collieries, and other situations where it is of importance for the unpractised eye to notice frequently the movements of the column without the careful observation necessary in the reading of an ordinary mercurial barometer. Water is apparently the most convenient liquid for a long range barometric column, and many water barometers have been constructed, notably that made for the Royal Society in 1830, by Professor Daniell. A water column is, however, of little use for indicating variations of pressure, owing to the effect of changes of temperature on the water vapour existing in the Torricellian vacuum, which often masks the effects which would otherwise be produced by changes of pressure. Having successfully constructed several water barometers, and finding this conflicting action caused by variations of temperature so detrimental to their value, I was induced to experiment with other liquids, and among those tried pure glycerine appeared to me to answer the purpose best. Glycerine from its high boiling point has a very low tension of vapour at the ordinary temperatures of the atmosphere; the length of the column is therefore only altered from changes of temperature by expansion and contraction of the liquid itself, and that in a very small degree, the mean coefficient of absolute expansion between 0° and 100°C. being ·0005455. The specific gravity of the purest glycerine as manufactured by Messrs. Price and Co. is 1·26, or less than one-tenth that of mercury; the mean height of the column is 27 feet at sea level, and a variation of a tenth of an inch in the height of the mercurial column is shown by a change of more than an inch in the glycerine; the boiling point is 440° F., and a very low temperature is required to solidify it. As glycerine absorbs moisture freely if exposed to the atmosphere, the action is prevented by covering the surface of the liquid in the cistern with a shallow layer of heavy petroleum oil, prepared especially for the purpose.

On the Construction of a New Glycerine Barometer

THE direct influence of changes of atmospheric pressure on the occurrence of many of our colliery accidents, so clearly demonstrated by the investigations of Messrs. Scott and Galloway, has naturally led to the consideration of barometers affording a wide range of movement, thereby rendering small atmospheric changes at once apparent, and clearly noticeable to the uneducated eyes of those engaged in such situations as collieries, storm stations, and other places where it is important fo note rapid movements without the careful observation which is requisite for the correct reading of an ordinary mercurial barometer.

A Mirror Barometer

M.LÉON TEISSERENC DE BORT has invented an aneroid mirror barometer, which is described in a recent number of La Nature. It is based on a method analogous to that well-known since the researches of Gauss for the reading of small rotations. M. Teisserenc de Bort has sought to obtain an aneroid barometer which will give precise observations at sea, especially in rough weather, when it is impossible to read the mercury barometer. The principle of this barometer is very simple. The elastic tub or box B carries, as in most aneroids, a metallic point, which follows its movements. In the ordinary aneroid the transformation of the vertical movement into a rotating movement necessitates either a chain or a curb, or a sort of fork which works in a spiral furrow cut in the axis which supports the needle. These various systems have the inconvenience of producing frictions; some of them are liable to dust and rust. In the mirror barometer, the transformation of the movement is obtained by the simple contact of a small palette supported on the axis of the mirror and of the point spoken of above. As the angle which the plane of the mirror may describe does not exceed 12° on each side of the vertical, it follows that the contact of the point in the palette is always precise.

An improved form of mercurial barometer

An improved form of mercurial barometer

2. Note on the Determination of Heights, chiefly in the Interior of Continents, from Observations of Atmospheric Pressure

The weight or pressure of the atmosphere is ascertained by the mercurial barometer, the aneroid, or from the temperature of the boiling point of water. The height of a hill is measured barometrically, from observations made simultaneously at its base and top, and the application of certain well-known formulæ. The height of a place at no great distance from another place whose height is known, and at which observations are made about the same time, may similarly be ascertained with a close approximation to the truth.But, with regard to places far from any place of known elevation, or from any place at which meteorological observations are made, it is plain that the height can only be computed by assuming a certain pressure as the sea-level pressure at that place.

III. Description of an improved mercurial barometer

Having shown this instrument to Mr. Gassiot, he wished me to write a short description of it, which he thought would be of interest to the Royal Society. Some time since I constructed an open-scale barometer, with a column of mercury placed in a glass tube hermetically sealed at the top, and per­fectly open at the bottom. The lower half of the tube is of larger bore than that of the upper.

XXXII. On a new self-registering mercury barometer

(1860). XXXII. On a new self-registering mercury barometer. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science: Vol. 20, No. 133, pp. 263-271.