Hasil untuk "Electricity and magnetism"

Teruo Matsushita

David Nightingale, Christopher Spencer

Louis A. Bauer

(For additional results, not given in the Abstract on page 23, the interested reader is referred to the summary of Chief Conclusions on page 186.)19. The atmospheric‐electric observations at Brussels, as shown by curves 2 and 3 of Fig. 3, were made from 1844 to 1877 with a Peltier electrometer “at noon every day,” and as Quetelet7 states, “with all the precautions which the determination of an element so difficult to measure as electricity requires.” Beginning with the middle of 1844, it would seem that the electrometer was mounted at an invariable height above the ground and protected as far as possible from disturbing influences. In calculating the mean results for any period Quetelet “avoided the use of negative values observed during abnormal periods.” While he at various times made a thorough discussion of his observations and investigated relationships between atmospheric electricity and meteorology, he does not appear to have considered, as I had been led to believe by an erroneous reference, any relationship with sun‐spottedness. If he had done so, he would probably have found difficulty in harmonizing the annual course of his results for the period 1845 to 1856 with that for the period beginning with 1856. Excepting for the irregularity in the Brussels8 annual values of P for the period 1871 to 1875, it will be seen from curves 1, 2, 6, and 7 of Fig. 3 that for the period 1855 to 1877, 22 years, increased potential gradient corresponded in general as well with increased sun‐spottedness as did increased magnetic activity (curves 6 and 7). The same fact is true with regard to the curve (No. 3) of “Average Departures of the Annual Variation of the Potential Gradient at Brussels.”

A. Nippoldt

It is characteristic of Gauss's method of working that he published no investigation until it was either finally completed or had been developed to the highest stage attainable at the time with the material at hand. Were there any weak points, no opportunity to point these out was neglected by him. Herein lies the classic value of his works, and so, naturally, it came to pass that for many years the principal endeavor of his successors was to fill in the missing links, and that only recently attempts have been made to farther develop his methods.In the field of terrestrial magnetism, especially, did further development of method take place but recently—hardly more than a decade ago. Since then, however, a wonderful zeal, enthusiasm, and singleness of purpose, as probably in no other branch of geophysics, have been displayed. This activity has disclosed a great number of new ideas and points of view, and has revealed a more intimate connection between terrestrial magnetism, meteorology, and atmospheric electricity than was at first suspected. This discovery, though but very recent, is leading future investigation into totally different paths from those of the earlier days.

M. Hinsenkamp

Are your students unimpressed with fleapower demonstrations of static electricity? Instead of picking up tiny bits of paper with a charged rod, why not turn them on with this forceful grabber!

S.P. STRELKOV, I.A. EL'TSIN, S.E. KHAIKIN

James Clerk Maxwell

Abstract on the explanation of .amp ère’s formula given by gauss and weber. The attraction between the elements ds and ds’ of two circuits, carrying electric currents of intensity i and i’, is, by ampere’s formula,