Sent postpaid on receipt of $2.00 (8s. 4d.)
Published by The Keystone,
the organ of the jewelry and optical trades,
19th & Brown Sts., Philadelphia, U.S.A.
SKIASCOPY AND THE USE OF THE RETINOSCOPE
A Treatise on the Shadow Test in its Practical Application to the Work of Refraction, with an Explanation in Detail of the Optical Principles on which the Science is Based.
This new work, the sale of which has already necessitated a second edition, far excels all previous treatises on the subject in comprehensiveness and practical value to the refractionist. It not only explains the test, but expounds fully and explicitly the principles underlying it—not only the phenomena revealed by the test, but the why and wherefore of such phenomena.
It contains a full description of skiascopic apparatus, including the latest and most approved instruments.
In depth of research, wealth of illustration and scientific completeness this work is unique.
Bound in cloth; contains 231 pages and 73 illustrations and colored plates.
Sent postpaid to any part of the world on receipt of $1.00 (4s. 2d.)