Gravity Balance Research Articles

Further history of a quartz thread gravity balance

A former paper* by one of the present authors and JAMES ARTHUR POLLOCK contains an account of the construction of a quartz thread gravity balance which was made at the University of Sydney during the time R. THRELFALL was Professor of Physics there. This work extended from 1889 up to the time of publication, and included an account of a good many gravimetric observations at Sydney, Melbourne, Hobart, and at various places in New South Wales. Final tests were made by taking the balance to and fro between Sydney and Hornsby, which is near Sydney but is 592 feet above sea-level, the University of Sydney, which was the Sydney observation station, being only slightly above sea-level (120 feet). As the result of several such journeys we finally felt entitled to say that “ We have therefore determined the value of g at Hornsby relatively to that at Sydney in three journeys with a maximum difference of 0.4 sextant minutes, or to less than 1 part in 500,000 in the value of g ." It had been intended to embark on a series of observations on the Australian coast, but, unfortunately, R. THRELFALL returned to England in 1898 and arrangements for carrying on the work had to be considered. J. A. POLLOCK succeeded R. THRELFALL as Professor of Physics at the Sydney University, and it was arranged that the balance, which, by the way, had been exhibited at the British Association Meeting at Dover, should be in J. A. POLLOCK’s charge and that he should continue the work in so far as his new duties as Professor of Physics enabled him to do so. Unfortunately, an opportunity never occurred and the balance was stored in one of the cellars of the Physical Laboratory of the University till 1923. Meanwhile Professor POLLOCK died.

Erratum: In Science Fields: Moon's Pull Measured by New Gravity Balance

Erratum: In Science Fields: Moon's Pull Measured by New Gravity Balance

The principles and practice of the gravity gradiometer

A description is given of the conditions in practical prospecting calling for a more portable, and rapid-acting gravity balance and leading up to the design of the gravity gradiometer. The dynamics of the suspended system of a gravity balance are investigated and the dynamical characteristics of the gradiometer indicated. A detailed description of the original instrument follows, with particulars of improvements incorporated in the latest pattern. Finally, a review of the field performance, as regards sensitivity and accuracy, of the gradiometer is given, with an account of a comparative test made on it in conjunction with a standard type of torsion balance. The gradiometer is shown to be a great improvement in the direction of portability and rapidity of action, and the design entails very little sacrifice of sensitivity. The latest pattern can be made five times as sensitive as the earlier model, without diminution of the rapidity of action.

STUDIES IN CENTRE OF GRAVITY CHANGES

Australian Journal of Experimental Biology and Medical ScienceVolume 10, Issue 1 p. 17-34 Original Article STUDIES IN CENTRE OF GRAVITY CHANGES 2. A NEW METHOD FOR DETERMINING THE ANTERO-POSTERIOR POSITION OF THE CENTRE OF GRAVITY IN MAN BY THE USE OF THE CENTRE OF GRAVITY BALANCE TABLE. FS Cotton, FS Cotton Department of Physiology, University of SydneySearch for more papers by this author FS Cotton, FS Cotton Department of Physiology, University of SydneySearch for more papers by this author First published: 01 March 1932 https://doi.org/10.1038/icb.1932.24AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume10, Issue1March 1932Pages 17-34 Journal of the Australian and New Zealand Society for Immunology RelatedInformation

The Determination of Clay and Colloid in Soils by Means of a Specific Gravity Balance

Soil Science Society of America JournalVolume B12, Issue 2001 p. 161-166 Article The Determination of Clay and Colloid in Soils by Means of a Specific Gravity Balance L. B. Olmstead, L. B. Olmstead Division of Soil Chemistry and Physics, Bureau of Chemistry and Soils, U. S. Department of AgricultureSearch for more papers by this authorL. T. Alexander, L. T. Alexander Division of Soil Chemistry and Physics, Bureau of Chemistry and Soils, U. S. Department of AgricultureSearch for more papers by this authorH. W. Lakin, H. W. Lakin Division of Soil Chemistry and Physics, Bureau of Chemistry and Soils, U. S. Department of AgricultureSearch for more papers by this author L. B. Olmstead, L. B. Olmstead Division of Soil Chemistry and Physics, Bureau of Chemistry and Soils, U. S. Department of AgricultureSearch for more papers by this authorL. T. Alexander, L. T. Alexander Division of Soil Chemistry and Physics, Bureau of Chemistry and Soils, U. S. Department of AgricultureSearch for more papers by this authorH. W. Lakin, H. W. Lakin Division of Soil Chemistry and Physics, Bureau of Chemistry and Soils, U. S. Department of AgricultureSearch for more papers by this author First published: 01 January 1931 https://doi.org/10.2136/sssaj1931.036159950B1220010025xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat VolumeB12, Issue20011931Pages 161-166 RelatedInformation

Gravity Balance May Be Divining Rod for Oil

Gravity Balance May Be Divining Rod for Oil

Gravity Balance as a Divining Rod for Oil

Gravity Balance as a Divining Rod for Oil

Gravity Balance as a Divining Rod for Oil

Gravity Balance as a Divining Rod for Oil

The E tv s Torsion Balance

The Eotvos Gravity Balance in the Science Museum, South Kensington, is described, and the theory of its operation considered. A full account is given of certain preliminary experiments made on the torsion wires, with a view to ascertaining the daily variation of the equilibrium position, due to strains set up in the wires during manufacture. Until this daily shift has been eliminated the instrument cannot be employed successfully. The experiments show that a preliminary treatment of the wires is desirable, and a test was also made of the baking method recommended by Eotvos for ageing the wires. This method was found to give the desired result, and after this treatment the reading of the instrument remained practically constant from day to day. Tables are given showing the variation in the reading of the instrument when its beam is rotated into different azimuths, and the constancy of these readings when repeated. The differences in the readings as the azimuth varies are sufficiently marked to indicate the changes in the local gravitational field of the laboratory, and further experiments are being carried out to determine these changes in detail, as a preliminary to field tests; it is hoped to communicate the results of these experiments at a later date.

A specific gravity balance for gases

A specific gravity balance for gases

Sensitive micro-balances and a new method of weighing minute quantities

In the course of experiments undertaken by the authors with a view to establishing a possible relation between the amount of ionisation produced at the surface of certain heated metals and the amount of oxidation of the metal, it became necessary to be able to measure changes of weight of the order of one-thousandth of a milligramme (1 X 10 -6 gramme). A micro-balance of the Nernst type was accordingly constructed which possessed the requisite sensitiveness, but considerable difficulty was experienced in obtaining consistent readings with it, owing chiefly to the inconstancy of zero and the great variation of sensibility with load. This latter defect is an inevitable consequence of the fact that a restoring couple due to gravity, the magnitude of which varies, as in the ordinary balance, with the position of the centre of gravity of the system relative to its point of suspension, is superposed on the restoring torque of the quartz fibre. Attempts to minimise this trouble led finally to the conclusion that for the purpose in view better results were to be expected from a gravity balance of the ordinary type in which the required degree of sensitiveness should be attained by making the beam very light. As the maximum load which it was intended to use on the balance was less than half a gramme, this could be done without loss of proportionate rigidity.

A Specific Gravity Balance for Large Rock Specimens

THE specific gravity balance represented in the accompanying illustration was devised by me some ten years ago for the determination of the specific gravity of hand specimens of rocks in the laboratory of the Geological Survey of India, Calcutta. In the ordinary form of Walker's balance the weight used on the short arm must be considerable in order to balance even a very small fragment of rock on the longer arm, and in consequence the specific gravity of an ordinary hand specimen has to be inferred from that of a small chip, which, unless the rock is of very homogeneous composition and texture, may give a very misleading result; and it is evident that if this form of balance were capable of accommodating a fairly large specimen, the whole instrument would have to be immoderately large. It occurred to me that if the specimen could be substituted for the heavy weight of Walker's balance, not only would it be possible to construct a balance of moderate size by which the determination of large specimens could be made directly, but the manipulation of the specimen and of the vessel containing the water might be greatly facilitated.

XII. A new current weigher and a determination of the electromotive force of the normal Weston cadmium cell

A Current can be measured absolutely in the electro-magnetic system of units either by means of the action of the current on a magnet, or of the current on a current. The former method has the disadvantage that at least two independent measurements are necessary. For example, in using an electro-magnetic balance, the strength of the magnet acted on by the electric circuit has to be determined, as well as the force exerted on the magnet by the circuit. In galvanometers, either of the sine or tangent type, the magnetic field produced by the electric circuit is compared with the earth’s horizontal field, the strength of which is determined independently. Further, as the strength of artificial magnets cannot be regarded as truly constant, and the earth’s field is subject to diurnal and secular variations, this class of measurement is not ideal. In the electrodynamic class of measurement the mutual action between two or more coils carrying current takes the form of a torque, as in electrodynamometers, or a direct force, as in current weighers. In electrodynamometers the torque may be measured with a bifilar suspension, the torsion of a wire or spring, or by means of a gravity balance. Current weigher measurements are almost always made by direct comparison with gravity, which is believed to be constant, and is known to a higher degree of accuracy than the strengths of any magnet or magnetic field that has yet been measured.

A FEW ARTICLES THE TINNER CAN MAKE FOR THE SCIENCE DEPARTMENT*

School Science and MathematicsVolume 3, Issue 2 p. 93-95 A FEW ARTICLES THE TINNER CAN MAKE FOR THE SCIENCE DEPARTMENT* W. E. BOWERS, W. E. BOWERS Seattle, Wash.Search for more papers by this author W. E. BOWERS, W. E. BOWERS Seattle, Wash.Search for more papers by this author First published: May 1903 https://doi.org/10.1111/j.1949-8594.1903.tb00692.x * Cf. “Some Experiences in Equipping the Laboratory”, Vol. I. p. 139; and “Specifications for a Cheap and Serviceable Specific Gravity Balance”, Vol. I., p. 477. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume3, Issue2May 1903Pages 93-95 RelatedInformation

SPECIFICATIONS FOR A CHEAP AND SERVICEABLE SPECIFIC GRAVITY BALANCE*

School Science and MathematicsVolume 1, Issue 9 p. 477-480 SPECIFICATIONS FOR A CHEAP AND SERVICEABLE SPECIFIC GRAVITY BALANCE* W. E. BOWERS, W. E. BOWERS Instructor in Physics, Tolt (Wash.) High SchoolSearch for more papers by this author W. E. BOWERS, W. E. BOWERS Instructor in Physics, Tolt (Wash.) High SchoolSearch for more papers by this author First published: February 1902 https://doi.org/10.1111/j.1949-8594.1902.tb00132.x * See this Journal, Vol. I., p. 158. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Volume1, Issue9February 1902Pages 477-480 RelatedInformation

On a quartz-thread gravity balance

The first part of the paper contains an account of the instrument in its present form, an account of the investigations leading up to the form adopted being relegated to an appendix. The principle of construction is as follows:—A quartz thread (which requires to be prepared with much care) is stretched horizontally between two supports, to which it is soldered. At one end the point of attachment is the centre of a spring of peculiar construction, designed so as to be capable of displacement in the direction of the thread, but incapable of any transverse motion or vibration.

II.—Walker's Specific Gravity Balance for Rocks and Minerals

The determination, by means of the chemist's balance, of the specific gravity of rocks and minerals, now more than ever an important element in their classification, is an operation of some difficulty. Various instruments of different kinds have been devised to obtain the same results more easily and expeditiously, and as amongst these there is one I had constructed some time ago and of which I have lately had very favourable reports from practical workers, perhaps an account of it may interest some of the readers of the Geological Magazine.

Scientific Serials

American Journal of Science and Art, November.—The original articles in this number are:-On the variation in the strength of a muscle, by F. E. Nipher.—Studies on magnetic distribution, by H. A. Rowland. This, Part I., is on linear distribution, and the scope is indicated by the titles of the sections: 1. Preliminary Remarks; 2. Mathematical Theory; 3. Experimental Methods for Linear Distribution; 4. Iron Rods magnetised by induction; 5. Straight Electro-magnets and permanent Steel Magnets; 6. Miscellaneous Applications.—Œstivation and its terminology, by Asa Gray.—A note in relation to the mass of meteoric iron that fell in Dickson County, Tenn., 1835, by J. L. Smith.—Specific gravity balance, by Roswell Parish. The object of this is to determine the specific gravities of minerals, and other solids heavier than water, without the use of exact weights and without mathematical computation.—A paper on Southern New England, by Prof. Dana.—Iowa county meteor and its meteorites, by N. R. Leonard.—On the post-Pliocene fossils of Sankoty Head, Nantuck Island, by A. E. Verrill. This article, referring to the paper by Desor and Cabot (Geol. Soc. Lond., 1849), purports to correct some matters of detail in that paper, and raises the number of known species from seventeen to sixty, of which a list is given.—In the short articles under “Scientific Intelligence” are:— Arithmetical relations between the atomic weights; Evidence of glacial action on the summit of Mount Washington; Discovery of the horns of an extinct species of ox in Ohio.—The two following reports are noticed: On the geology and resources of the region in the vicinity of the 49th parallel from the Lake of the Woods to the Rocky Mountains; A reconnaissance of the Black Hills of Dakota made in the summer of 1874.—In an appendix Prof. O. C. Marsh contributes a paper on the Odontornithes, or birds with teeth. After recapitulating facts he has already contributed, he gives this classification:— Sub-class, ODONTORNITHES: A. Teeth in sockets; vertebræ biconcave; sternum with keel; wings well developed; order, Ichthyornithes. B. Teeth in grooves; vertebræ as in recent birds; sternum without keel; wings rudimentary; order, Udontolcæ. There are two plates in illustration of this paper.