scholarly journals A new current weigher, and a determination of the electromotive force of the normal weston cadmium cell

1907 ◽  
Vol 80 (535) ◽  
pp. 12-18
Keyword(s):  
Current Sheet ◽  
Electromotive Force ◽  
Unit Length ◽  
Screw Thread ◽  
Late Professor ◽  
Convenient Formula ◽  
Association Meeting ◽  
Helical Current ◽  
Mutual Induction

The instrument described is the outcome of conversations between the late Professor J. Viriamu Jones, F. R. S., and one of the authors (W. E. A.), on their return from the British Association Meeting held in Toronto in 1897. Its object was to determine “ the ampere ” as defined in the C. G. S. system, to an accuracy comparable with that attained in the absolute determination of the ohm by Lorenz’s apparatus, an account of which was given by Professors Ayrton and Jones at the Toronto Meeting. Professor Jones had previously developed a convenient formula for calculating the electromagnetic force between a helical current and a coaxial current sheet, viz., F = γ h γ (M 2 -M 1 ),† where γ h is the current in the helix, the γ current per unit length of the current sheet, and M 1 , M 2 the coefficients of mutual induction of the helix and the two ends of the current sheet respectively. By using coaxial coils with single layers of wire wound in screw-thread grooves, advantage could be taken of the above formula.

scholarly journals On the calculation of the coefficient of mutual induction a circle and a coaxial helix, and of the electromagnet force between a helical current and a uniform coaxial circular cylindrical current sheet

1898 ◽  
Vol 63 (389-400) ◽  
pp. 192-205 ◽  
Keyword(s):  
General Solution ◽  
Current Sheet ◽  
Electrical Resistance ◽  
Circular Disc ◽  
Mcgill University ◽  
The Mean ◽  
Helical Current ◽  
Mutual Induction

1. In measuring electrical resistance by the method of Lorenz have to determine the coefficient of mutual induction of a helix wire and the circumference of a rotating circular disc placed coaxially with it, the mean planes of the helix and the disc being coincident. In a paper presented to the Physical Society November, 1888, I gave a method of calculating this coefficient; by subsequent consideration of the problem in connection with the Lorenz apparatus recently made for the McGill University, Montrea has led me both to a simplification of the method previously described, and also to a more general solution. 2. If M is the coefficient of mutual induction of any two curve we have M = ∫∫cos ϵ / r dsds' , where r = the distance between two elements ds, ds' ; and ϵ = the angle between these elements.

scholarly journals On the calculation of the coefficient of mutual induction of a circle and a coaxial helix, and of the electromagnetic force between a helical current and a uniform coaxial circular cylindrical current sheet

1898 ◽  
Vol 62 (379-387) ◽  
pp. 247-250
Keyword(s):  
Current Sheet ◽  
Electromagnetic Force ◽  
Extreme Points ◽  
Helical Angle ◽  
Helical Current ◽  
Mutual Induction

1. Let M Θ be the coefficient of mutual induction of a circle and a portion of a coaxial helix, beginning in the plane of the circle and of helical angle Θ. Then if M is the coefficient of mutual induction of the circle, and any portion of the helix for which the extreme points are determined by helical angles Θ 1 and Θ 2 , we have M=M Θ 2 –M Θ 1 . It will therefore be sufficient to show how to calculate M Θ for all values of Θ.

IV.—Notes on the Bivalves contained in the Gilbertson Collection, British Museum, and Figured in Phillips's “Geology of Yorkshire.”

1879 ◽  
Vol 6 (4) ◽  
pp. 161-165
Author(s):  
R. Etheridge
Keyword(s):  
Accurate Determination ◽  
British Museum ◽  
Great Difficulty ◽  
Type Specimens ◽  
Early Date ◽  
Late Professor

BY far the larger proportion of the Carboniferous fossils described and figured by the late Professor John Phillips, F.R.S., in the second volume of his “Illustrations of the Geology of Yorkshire,” and published in 1836, are contained in the collection of the late Mr. Gilbertson, of Clitheroe, now deposited in the Geological Department of the British Museum. The early date of publication of this work renders the collection described in it one of the most important, next to those of Sowerby, Ure, Martin, and one or two others, to students not only of British, but equally so of Continental Carboniferous Palæontology. Unfortunately the descriptions of Prof. Phillips are so abbreviated and unsatisfactory, and the figures in many instances so mearge, that it is with great difficulty anything like an accurate determination of a species can be made by the aid of them. Under these circumstances the following notes made directly from the type specimens will probably be found of use; it would, however, be far more satisfactory to have the specimens refigured. For convenience sake I shall commence with those composing plate vi., and then take the others composing plate v.

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