The velocity of accommodation / by James W. Barrington.

  • Barrett, James W. (James William), Sir, 1862-1945.
Date:
[1885]
Catalogue details

Licence: Public Domain Mark

Credit: The velocity of accommodation / by James W. Barrington. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    THE VELOCITY OF ACCOMMODATION. By JAMES W. BAERETT, M.B. (Melbourne), Demonstrator of Physiology in Kings College, London. Introduction. The experiments on which this communication is based, and their general mode of conduct, have been subjected to the supervision of Professor G. F. Yeo, by whose kind assistance many of the detailed parts of the apparatus with which the measurements have been made were arranged. Mr W. Lang (of Moorfields) has also devised several additional ap- pliances for facilitating the work, notably the method of estimating the accommodation velocity with binocular vision. Further Mr Stanford Morton has materially assisted the writer, who feels that the effectiveness of the apparatus he has used depended in great measure on the kindness of his friends. It would appear that but few workers in physiology have attempted to ascertain the time occupied by the act of accommodation. The first, as far as the writer is avvare, who examined the subject experimentally was Volkmann^ who when discussing the motion of the eye, in his article **Sehen in Wagner's Dictionary, states that by an application of Scheiner's method he found that in half a minute he could change his accommodation 20 times from 11 to 6 inches and back again. This gives an average of 1'5 seconds for each movement but makes no distinction between alteration from far to near and from near to far. The first who devoted a special work to the subject was Vierordt^, who by means of a chronoscope determined the duration of the acts of changing the accommodation of his practised left eye to and from a fixed object situated at 1819 cm. and another at a varying near point. The objects were diagonally placed threads. He found that the rate varied 1 Wagner's Handworterb. d. Physiol. Bd. in. p. 309. 2 Versuche iiber die Zeitverhaltnisse des Accommodationsvorganges im Aiige. Arch. f. physiol. Heilkunde, N. F. Bd. i. 1857.