In 1934, a small group of young men, imbued with a mutual interest in astronomy and a curiosity about the tools of the astronomer, organized themselves into the New York Telescope Makers Association. With the erection of the Hayden Planetarium in 1935, a new focal point of astronomical interest was created for the New York metropolitan area. Shortly thereafter the telescope making group became a part of the Amateur Astronomers Association, an organization now of about 500 members, sponsored since 1927 by the American Museum of Natural History. Facilities and space for the telescope makers were provided in the basement of the Planetarium, where they began activities as the Optical Division of the Amateur Astronomers Association. As such I learned of the group and was privileged to become a member.

The Optical Division presently undertook classes in telescope mirror making, an activity which had been expanding from earlier beginnings at the Museum. With the advent of the war and the absence of some of our most skilled and active members, your author was asked to assist in carrying on with the teaching program, and has continued in this capacity to the present time.

In these classes, numerous problems arose that interest but perplex the tyro concerning the telescope and its parts, its functions and its optics, its capabilities and its limitations, and other related matters. The answers to many of these problems are as widely dispersed as amateur astronomers themselves, and are probably not to be found in any single volume in the consecutive and integrated arrangement which would be most useful to the beginner. Hundreds of mirrors in various stages of incompletion, made by amateurs working independently at home, have been brought to the author to have their ills analyzed.

In the light of these experiences, it seemed that the sort of service and instruction rendered at the Planetarium might worthily be made available to a greater number of amateurs. Accordingly, a series of articles on telescope making was prepared, and published in Sky and Telescope. These articles were received with much favorable mention, and it was therefore decided to expand and publish them in book form. And so this volume was born. In it the author has attempted to guide the novice past those pitfalls and snares into which the untutored worker is likely to stumble. Some new techniques are described, enabling excellent optical surfaces to be fashioned in a shorter time than heretofore generally required. The other parts of the telescope have not been neglected, and considerable study is devoted to the design of the various supporting parts. Descriptions of simple pipe mountings of proven efficiency are included. Endeavor has also been made to supply the answers to many questions not elsewhere treated. Some of the diagrams previously used have been redrawn and the number of illustrations has been more than doubled.

We are indebted to Earle B. Brown, an associate in the Optical Division, who read the original manuscript of the Sky and Telescope series, and made many corrections and valuable suggestions. Acknowledgment must also be made to Charles and Helen Federer for their patient help in the arrangement of the material and for the order of presentation.

An expression of gratefulness is also made to the Amateur Astronomers Association and its officers, and the members of the Optical Division, all of whom by their interest and active support have helped make this book possible.

Allyn J. Thompson
New York, April 15, 1947

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