"I am sending you," Mr. Norvell writes "a snap shot of my l6-inch reflector. The mirror was made of inch and one half glass. I took my time and did not let the surface get scratched, nor did I have difficulty with sticking. I did have quite a time landing a good correction on the glass but I had previously made two 10-inch mirrors and this helped wonderfully.

"I ground the mirror to a focal ratio of 11 to 1. This is quite long, but it gives a fine fiat field, and when seeing is good it is hard to beat. The glass shows no flexure but I would not advise anyone to attempt a larger mirror with such thin glass. Anyone who wishes to try a 16-inch will surely have to be careful, as it is altogether more of a job than a 10-inch.

"I can see with the telescope white objects, looking like foam, on the sun; also good markings on Mars; Jupiter's fine markings from pole to pole; and Saturn's rings and divisions.

"The tube is 16 feet in length and 19-inches in diameter. The mounting is made of pipe; the polar axis is 4-inch pipe turned in a lathe to fit a brass box. The whole outfit is set in concrete. It took 215 pounds of old babbit metal to provide a heavy enough counterweight.

"You will notice I have a sliding roof over my refractor, running on balls.

"I do not know what I shall try next, but am thinking of attempting a spec, troheliscope."

FRANK L. WATTS, Box 637, Silvis, Illinois, has made a Cassegrainian telescope. Mr. Watts writes as follows:

"Enclosed is a photo o my 6-inch Cassegrainian telescope This is my first attempt at making one of this type. The small convex mirror gave me some little trouble in correcting but I succeeded in the end, so that the best of definition is had.

"I get nearly as good results with this as with my 9-inch Newtonian reflector. and fully as good as with my 6 inch refractor. Owing to the long focal length the image is better near the edge of the field than in either of these other telescopes.

"In correcting for figure I did all the testing with a 10-ineh flat, and find this gives far better results than by the ordinary method.

"I have interested several parties in this work and expect to build a 16-inch. I have a well equipped shop and will be pleased to help anyone wishing to build a telescope.

"I wish to thank you very much for aiding me, through your literature."

BELOW we quote a fragment or two from a recent letter from Reverend W. F. A. Ellison, author of the original book "The Amateur's Telescope," most of which is now embodied in "Amateur Telescope Making." Last autumn the Telescope Editor spent a most interesting day wit) Ellison at the Armagh Observatory in Northern Ireland. A photograph of this delightful old place with its surrounding parks of yew trees and shrubs is reproduced in these columns. The Observatory was built about 1790 and is now used as a residence. It also houses a number of old telescopes and transits which are now curiosities. Carefully put away in a box was a neat brass reflector, about a 6ineh, used by King George III, who was an amateur astronomer. The two modern observatory domes do not show in the picture. One houses a 10-ineh, the other an 18-ineh, reflector; both of which are used by Ellison. He also maintains a government meteorological station.

One corner of Ellison's workshop building, a thick-walled stone structure, is visible at the extreme right. As one might safely anticipate, this work room in which the superlative Ellison mirrors are made by hand, was utterly simple-no complicated apparatus, no "patent dingbats," no pretension. The testing stand was as plain as one which might be built to test a single mirror. Of course, an expert's main stock of "apparatus" is under his skull. Reverend Ellison stated that he has now completed 140 mirrors, instead of the 70 mentioned in A. T. M.

To visualize this mentor of the amateurs the reader may think of a tall, large-framed, striking individual of about 50, with swarthy black beard, dressed in the cloth of the clergyman, with the leggings, the low broad hat and other habiliments of the protestant "Church of Ireland." He, it turned out, is also an expert organist, and his performance on the great electric organ of the Armagh Cathedral was equal in quality with his performances on optical surfers.

Rev. Ellison writes: "I am afraid your people over there have gone ahead of my reach altogether. If I started the movement, I was like the small boy that rolled a stone down the mountain and started an avalanche. So, far from landing a lovely job like your Mr. Porter I am sometimes afraid 'The Amateur's Telescope' has knocked the bottom out of my market. Still, I am glad to think I have helped so many folks. Tell Mr. Porter, as well as the rest of the brotherhood of 'C. P. R.' (that is, not Canadian Pacific Railway, but ' Carborundum, Pitch and Rouge') that I wish 'more power to their elbows,' and I hope they will not forget the fellow who set the ball rolling.

"The real difficulty about 16- and 21-inch jobs is in the mounting and using. I know from my experience with an 18 inch that observing with a 21 inch is no picnic.' (Later we shall explain this.-Ed.)

RECENTLY several have asked why we did not pay more attention to observations and things actually done with the telescopes already in use by amateurs. One reason is that we lack the space to publish them in the magazine. We shall then, confine ourselves in this department more to the mechanical end of the work and we suggest that descriptive observations be submitted to our esteemed contemporary, Popular Astronomy (Northfield Minnesota). That journal has recently started a special department for amateur observers. These reports of such observations should be condensed as much as possible.

One type of "observation" which does bear directly on mirror making-specifically on mirror figuring-is the matter of resolving power of a telescope, as determined by its ability to separate close double stars. A. R. Dunlop of New Westminster British Columbia, suggests that all the amateurs send in brief statements of the closest double stars their telescopes will separate-a good idea, especially in view of the fact that one telescope maker, a noted professional, once stated to us that he had seen no amateur mirrors with really good figures. We believe he has not seen a representative lot. How can we convince him there are better ones?

Send in your best examples of double star dividing. For the theory of resolving power see Bell, "The Telescope."

IN the July number we broached the question of popularizing seismology, and asked interested readers to write to us. The response was not exactly overwhelming, but we did not expect seismology to make the same killing amateur telescope making did when we broached that subject in November, 1925. A well known scientist has now sent us, for later publication, the description of a small seismograph of a special type which, to judge from the photographs and drawing, should give the constructor just enough worry to make him feel the job was worth while doing.-A.G.I., Tel. Ed.

The Society for Amateur Scientists (SAS) is a nonprofit research and educational organization dedicated to helping people enrich their lives by following their passion to take part in scientific adventures of all kinds.