WORLD’S BIGGEST TELESCOPE

Dominion, Volume 32, Issue 258, 29 July 1939, Page 6 (Supplement)

WORLD’S BIGGEST TELESCOPE

On Mount Palomar In California

Six thousand feet up in the San Bernardino mountains of Southern Cali fornia, 80 miles uorth-east of San Diego, on the top of Mt. Palomar, there rests a giant steel dome which encloses the most complete astrophysical laboratory in the world, says the London “Times.” On its huge floor today lie 500 tons, of parts which by the beginning of next year will have been completely assembled and mounted to make up the world’s largest telescope, 75ft. high, with a 200 in. mirror.

For two years special trains and carriers have brought enormous and delicate parts across the continent, tractors have dragged them up the mountain aud into the dome. There for four years a small colony of 75 skilled men and 20 women have worked on the assembling, and iu the process have evolved a community complete with its own water supply, telephone system aud school for their children. By the spring of 1940 most of them expect that their trying exile will be over and they will be able to so down again to enjoy the natural changes of the season, for their work has gone on at a temperature controlled so as not to vary more than three degrees night and day, winter and summer.

The problems of construction were vastly complicated, but were in time resolved into two undertakings. Before the council could proceed to the main task—namely, to produce the mirror - they had to be sure they could construct a mounting sufficiently sensitive to swing the mirror on a frictionless base. And to justify the titanic effort and cost the council concluded they would first have to guarantee that they could produce a mirror which would take and hold a good figure with hardly any expansion or contraction under temperature changes, a mirror which would have to be true to two-millionths of an inch. They started by investigating every known type of glass, of speculum metal and hard alloys such as stellite, obsidian and natural crystals. After exhaustive studies all these were found to have faults. They were reduced to experimenting with fused quartz, which had the lowest known coefficient of expansion for their purpose. On. March 25. 1934, in the Corning

glass factory the first attempt was made to pour the disc. The pouring went on all day, the molten glass being carried in 100 ladles on trolleys to the mould, which was kept at 2000ileg. Fahrenheit. Some of the mould projections broke and floated to the top. Ute experiment was thought to be ruined and the first pouring discounted, hut it later turned out that this bad produced a successful disc which thus accidentally offered to the world an additional 200 in. low expansion glass. They tried again some time later and the disc was sucessfully poured, and after 10 hours was safe in the annealing oven, where it remained to cool for 11 months.

The complementary work in the task, how to construct a moulding on which the monster mirror could be swung by hand, was a feat which in prospect and now iu retrospect appears as astonishing as the construction of Boulder Dam and Lake Mead. In the excited speculation about what the new telescope will do, there have been many foolish claims made by journalists confusing the size of the mirror with its possible magnification. The Mount Palomar telescope will magnify no more than many smaller telescopes, no more for instance than the adjacent 48in- Schmidt, which it will employ as a “scout." We shall learn little or nothing that is new about the earth’s nearest neighbours. But this new telescope will see further into space than has been done since the day in the 17S0’s when Herschel discovered with reflecting telescopes the composition of the Milky Way. The new telescope will lie able to see a billion light years into space. It may, next year, begin to tell us about worlds and galaxies we do not know. Through the 30ft. wide slit in the steel eyelid of the Mount Palomar dome we may even learn more about the transformation of atoms into energy and of energy back again into matter. Mount Paiomar gives to mankind a unique scientific instrument of ' incalculable value, and incidentally adds to the West another of the technological marvels in which the United States so consistently excels..