Price, $3.50 (14s. 7d.)

PUBLISHED BY THE KEYSTONE,
THE ORGAN OF THE JEWELRY AND OPTICAL TRADES,
19TH & BROWN STS., PHILADELPHIA, U.S.A.

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OPHTHALMIC LENSES

Dioptric Formulae for Combined Cylindrical Lenses, The Prism-Dioptry and Other Original Papers

BY CHARLES F. PRENTICE, M.E.

A new and revised edition of all the original papers of this noted author, combined in one volume.  In this revised form, with the addition of recent research, these standard papers are of increased value.  Combined for the first time in one volume, they are the greatest compilation on the subject of lenses extant.

This book of over 200 pages contains the following papers: 

  Ophthalmic Lenses. 
  Dioptric Formulae for Combined Cylindrical Lenses. 
  The Prism-Dioptry. 
  A Metric System of Numbering and Measuring Prisms. 
    The Relation of the Prism-Dioptry to the Meter Angle. 
    The Relation of the Prism-Dioptry to the Lens-Dioptry. 
  The Perfected Prismometer. 
  The Prismometric Scale. 
  On the Practical Execution of Ophthalmic Prescriptions involving Prisms. 
  A Problem in Cemented Bi-Focal Lenses, Solved by the Prism-Dioptry. 
  Why Strong Contra-Generic Lenses of Equal Power Fail to Neutralize
    Each Other. 
  The Advantages of the Sphero-Toric Lens. 
  The Iris, as Diaphragm and Photostat. 
  The Typoscope. 
  The Correction of Depleted Dynamic Refraction (Presbyopia).

Press Notices on the Original Edition:

OPHTHALMIC LENSES.

“The work stands alone, in its present form, a compendium of the various laws of physics relative to this subject that are so difficult of access in scattered treatises.”—­New England Medical Gazette.

“It is the most complete and best illustrated book on this special subject ever published.”—­Horological Review, New York.

“Of all the simple treatises on the properties of lenses that we have seen, this is incomparably the best....  The teacher of the average medical student will hail this little work as a great boon.”—­Archives of Ophthalmology, edited by H. Knapp, M.D.

DIOPTRIC FORMULAE FOR COMBINED CYLINDRICAL LENSES.

“This little brochure solves the problem of combined cylinders in all its aspects, and in a manner simple enough for the comprehension of the average student of ophthalmology.  The author is to be congratulated upon the success that has crowned his labors, for nowhere is there to be found so simple and yet so complete an explanation as is contained in these pages.”—­Archives of Ophthalmology, edited by H. Knapp, M.D.

“This exhaustive work of Mr. Prentice is a solution of one of the most difficult problems in ophthalmological optics.  Thanks are due to Mr. Prentice for the excellent manner in which he has elucidated a subject which has not hitherto been satisfactorily explained.”—­The Ophthalmic Review, London.