The illustrated optical manual, or Handbook of instructions for the guidance of surgeons in testing quality and range of vision, and in distinguishing and dealing with optical defects in general / by Surgeon-General Sir T. Longmore.

  • Thomas Longmore
Date:
1888
Catalogue details

Licence: Public Domain Mark

Credit: The illustrated optical manual, or Handbook of instructions for the guidance of surgeons in testing quality and range of vision, and in distinguishing and dealing with optical defects in general / by Surgeon-General Sir T. Longmore. Source: Wellcome Collection.

Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.

    46/296 (page 18)
    times spoken of as finite rays, and the divergency of such rays increases in proportion to the proximity of objects to the eye. On referring to fig. 17, il will be seen thai the whole of the divergent pencil of rays proceeding from the luminous point F is intercepted by a b at 1 foot. Al - feet a considerable portion and at further distances increasing proportions <>f the external rays pass on without interruption, while the rays intercepted arc the more centra] ays until al I ■> feel thej would be practically parallel.