"Living in a closely built up section in Allentown, with high buildings and bright lights all around me, which interfere so much with this work that it is very unsatisfactory, I made the telescopes portable so that I can take them out into the country or to some open space where I have a good view of the sky and can be away from the bright lights. For this reason I am using a tripod.

"The mounting of the Newtonian telescope is made of steam fittings. I used a 45 degree angle, a 90 degree angle, three close nipples and two floor flanges. When I assembled these I had an equatorial mounting; giving me motion in right ascension and in declination. Using the threads for bearings, I have a very easy and steady motion of the telescope. However, the nipples plumbers keep in stock are all tapered from the middle toward the ends. They are especially made this way to make steam-tight joints, but they do not work well in a telescope mounting, so I had straight nipples made by a machinist.

"I live in latitude 40 degrees 43 minutes, so the 45 degree angle is just a little more than four degrees short of a polar axis. To correct this I tilt my tripod just a little toward the north and thus I get an approximate polar axis. If I were to put this mounting on a concrete post or a section of a water main, I would correct it by putting a wedge under the base flange, and tilting the mounting enough so that the 45 degree angle would point exactly to the pole of the heavens."

William J. Davis, 7736 Elmgrove Drive, Elmwood Park Illinois, has discovered that an old swivel chair need not be retired to the attic or sent to the junk-heap. He writes: "After giving my telescope a six month trial, I believe it is time for me to tell the Telescope Editor about it. My mirror is a six-inch, ground and polished to a focal length of 45 inches. I made my own diagonal and two low-power eyepieces. The mount is from a discarded swivel chair, with the seat removed and the end of the legs cut off.

"I believe I have an exceptionally good parabolic mirror because of the good definition I sometimes get of the stars when using a quarter inch eyepiece. I don't see why anyone should stand up and bend over to polish a small size mirror. I used a table and sat down during the whole process."

G. C. Hanley of Mincha (no state, no country, mentioned) sends in a brief note about his telescope, with two photographs. He writes on the letterhead of the "Mincha Butter Factory-Pasture Gold Butter." No acknowledgement could be sent him because the address was incomplete. No Mincha is listed in the United States Postal Guide, and none appears in our gazeteer of the world. However, we located Mincha-at least we believe it is somewhere on earth, and presumably not far from one of the two 36th parallels of latitude. A protractor placed on the polar axis of the telescope in the illustration proves this. There is no clue, however, to the longitude, but one of the photographs (not reproduced) shows a tree that looks exotic. Our hunch is therefore-Australia. Down there a polar axis is still parallel to the earth's axis but it points south, not north (its lower end points north). The Sun daily crosses the northern, instead of the southern, heavens; but it still rises in the east. In short, everything is mixed up -which is probably just what an Australian amateur thinks about things up here "on -top" instead of "down under," where he lives. Mr. Hanley writes:

"I am sending you some photos of the eight-inch telescope I made with the help of the article in the SCIENTIFIC AMERICAN. This is the second telescope I have made. The first was a four inch. It had a good mirror except for a turned-down edge. The eight-inch mirror had a raised zone, but after a few nights' work I got it figured correctly.

"The mounting is made almost entirely from pipe fittings and old Ford parts. Slow motion is obtained by having a lug on the edge of the friction disk, coupled to a long threaded bolt. This method gives good control. I have not yet fitted the slow motion control to the declination axis The telescope controls very well as it is.'

Amateurs whose telescopes are complete will find plenty of serious work to perform with them. One possibility is contained in a paper entitled "Photographs of Venus' by Prof. Frank E. Ross of Mt.- Wilson Observatory, published in Number 1 Volume 68, of the Astrophysical Journal To quote: "In view of the success of Mr. Rordame in securing photographs of marking of this nature in full daylight, field offering results of value is opened t amateurs possessing only very modes equipment." In the work referred to nine-inch refractor had been used, and markings on Venus were photographed o commercial film. A 12-ineh reflector should easily give comparable results; eve a 10-inch might.

Someone has raised the question: Who first originated the common method grinding and polishing specula-the equal sized disk and tool method, in contradistinction to the older small-tool method. The credit for this discovery evidently belongs to Dr. Elihu Thomson, now Director of the Thomson Research Laboratory the General Electric Company, a Corresponding Editor of this journal. In 1878 Dr. Thomaon described it in the Journal of the Franklin Institute as 'A New Method of Grinding Glass Specula,' The question was referred to Ellison, who also believes Thomson deserves the credit. He suspects Short, an early professional, had previously hit upon the same method. about 1750. If so, he kept it a secret, and therefore deserves no credit.

Finally, a bit of good news: our friend Russell W. Porter, by common consent the leader of all the American amateur telescope makers and co-author of "Amateur Telescope Making," has been honored by a call to California by those who are in charge of plans for the new 200-ineh telescope. The project is co-operative between California Institute of Technology and Mount Wilson Observatory. Mr. Porter will take part in the design of the instrument and optical shops required in connection with the new Astrophysical Observatory, and will also co-operate on the design of the great 200-ineh telescope and other instruments. He retains his connection with Vermont, but he has also been designated Associate in Optics and Instrument Design at the California Institute of Technology. All amateurs will wish him success and follow his progress with keen interest.-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.