28 APRIL 1900, Page 8

Telephotography : an Elementary Treatise on the Construction and Application

of the Telephotographic Lens. By Thomas R. Dallmeyer, F.R.A.S. (W. Heinemann.)—This process gives a greatly ex- tended range to photography, and will add much to our know- ledge of distant things. Not only can we get pictures of birds in their nests at the tops of trees, but the officer in the field can make records of the enemy's country at the distance of many miles. There are a number of reproductions of photographs, and it is interesting to compare the points of view of the ordinary and the telephoto lens. The mathematical and optical side of the question is fully discussed.