A simplified moving magnet galvanometer with a high figure of merit

Downing, A C

doi:10.1088/0950-7671/3/10/302

Cited by 9 publications

(4 citation statements)

References 2 publications

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“…By measuring the period of the system under these conditions we can obtain some idea of the extent to which one complex is stronger than the other. 2 TO TWO STIMULI. 3 This N.-S. component has now to be abolished, and this can be done either by the addition of a tiny magnet to strengthen the weaker complex, or by inducing opposite polarity in the stronger complex, thus strengthening or weakening one complex or the other until the two are more nearly equal.…”

mentioning

confidence: 99%

The electric response of nerve to two stimuli

Amberson¹,

Downing²

1929

The Journal of Physiology

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confidence: 99%

The electric response of nerve to two stimuli

Amberson¹,

Downing²

1929

The Journal of Physiology

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“…Being-like all moving-coil galvano meters-completely unaffected by external magnetic fields, they eliminate one serious source of error. Where great quickness of response, or extreme sensitivity, is required, they are still considerably inferior to a good movingmagnet galvanometer, e.g., of the type designed by Downing (1). For general purposes, however, in myothermic measurements, their various advantages, and their simplicity in the hands of a novice, make them far the best recording instrument at present available.…”

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confidence: 99%

Myothermic apparatus

1928

Proc. R. Soc. Lond. B.

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Myothermic Apparatus. % 117 Conclusion.The evidence at hand is still somewhat scanty and diffuse, and from the nature of the case it is difficult to accumulate detailed analyses of the combined fatty acids in various seed fats at anything but a very slow rate. Neverthe less, the facts set out above render it evident that, in the four orders discussed, there is a marked tendency towards the production of quite specific fatty acids. Other acids, of course, are also present, oleic and linoleic acids usually in fair to considerable proportions, and also minor amounts of such acids as palmitic, arachidic or lignoceric; but the four acids, lauric, myristic, erucic and petroselinic, stand out quite definitely in their nature and proportion in the respective cases of the four orders, Palmce, Myristicece, Cruoiferce and It is to be inferred that the seed fats of any given botanical order have certain characteristics of their own, and much in common with each other, differing from those of dissimilar orders.

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“…Subtracting the reading for a single maximal shock from the reading for two shocks at any desired interval, the magnitude of the electric response to the second stimulus can be determined. 3. A curve is given for the gradual return of the action potential to its full value as the interval after the preceding shock is increased.…”

Section: Discussionmentioning

confidence: 99%

Note on the electric response of nerve to two stimuli

Zotterman¹

1928

The Journal of Physiology

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IN a previous paper by Gerard, Hill and Zotterman(i) on the effect of frequency of stimulation on the heat-production of frog's nerve, the return of the power of liberating energy after a previous impulse was given as a function of the interval between the stimulus and its predecessor. The "total action current" also at various frequencies of stimulation was recorded with a sensitive Downing galvanometer, and it was shown that this bears a relation to the frequency of stimulation which is very similar to that shown by heat liberation.It was evident from these experiments that the power of liberating energy, as well as that of developing action potential, did not return completely to its full value in less than 50 a after stimulation. From the work of Lucas and Adrian(2) it is well known that the return of excitability in a frog's sciatic nerve is complete in about 15 a, and it has been shown that the return of the power of propagating the disturbance coincides with the return of excitability. The curve of recovery of excitability, however, was constructed by measuring the least interval for minimal muscular summation, and is therefore an expression of the return of excitability of the quickest motor fibres only of the nerve, while the experiments of Gerard, Hill and Zotterman referred to all the fibres. It was obviously desirable to confirm the results obtained on nerve stimulated at various frequencies, by observations on the total electric response to two stimuli only, with various intervals between them. This is readily done owing to the extreme sensitivity available in the high resistance Downing galvanometer employed.Method. The nerve was placed in a Lucas chamber. The stimulating electrode was placed at the spinal end, non-polarisable electrodes of the zinc-zinc-chloride-gelatin-Ringer type at the distal end; one of these was 1 Fellow of the Rockefeller Foundation.

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A simplified moving magnet galvanometer with a high figure of merit

Cited by 9 publications

References 2 publications

The electric response of nerve to two stimuli

The electric response of nerve to two stimuli

Myothermic apparatus

Note on the electric response of nerve to two stimuli

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