The daily morning journal and courier., 1901-06-17
THE GREAT PARIS TELESCOPE.
The Largest in the World, but of Nc
 Use as Yet to Science.

| HE GREAI PARIS IELESCOPE
 The Largest in the World, but of No
 Use as Yet to Science
 What is the great Paris telescope
 doing?" is question that must soon
 be answered If the instrument is to
 justify its existence. It's promoters
 had in view a higher purpose than to
 provide a gazing-stock for the visitor
 to the exhibition; they were without
 doubt genuinely anxious that their en-
 terprise should add to the equipment of science an instrument of extreme value, And yet there have been no in dications of any attempt to use the tel escope seriously for serious astronomi- cal work. It has produced some pho- tographs of the moon, which were pub lished not long ago in magazine, and they are probably the worst examples of lunar photography that have ever seen the light, immeasurably inferior to De la Rue's great photograph made forty years ago, and not to be com- pared with the work which dozens of smaller instruments could produce to- day. Yet in all seriousness M. Delon- SiC VI illiSS lilCll lOl NGlu tAo N<AoA'iPiSP va the work of his instrument, and speaks of the poor things as "epoch- marking | photographs"
 Now to publish these photographs at all, still more to seem to be contented with them, argues such lack of scien- tific judgment in M. Deloncle as to warrant the inquiry: How dir this great instrument come to be built. and what hope is there that it will be Of real service to astronomy? To the first question the promoter of the scheme has himself supplied the answer He spent an evening, he says, at the Paris Observatory and watched M. Loewy at work on his beautiful photographic at las of the moon. If you had an in- strument more powerful you could ob- tain even better results?' "Undoubt- edly" In an instant, he tells us, his | resolution was formed. He would build a larger telescope than had ever been made before "As I anticipated, the project at once captured the popular 1 imagination and La lune un metre became in a day one of those catch words that fly round the world as fast as the telegraph can take them l IL IS ullllCull, III lliC loSS pi Niii' NoA' ously unscientiflc confession. to absolve NM. Deloncle from responsibility for the nonsense with which the sensation al press forthwith overf1owed. The moon was to be brought within an ap- parent distance of few metres; Mars was to be projected on secreen to form an image nine metres in diame- ter; the nebulae were in lige manner to be exhibited in q theater to many hun dreds at one time. The project was manifestly absurd. Is 1t possible with an object glass of fifty inches aperture to form on a screen an image of Mars thirty feet in diameter?
 The question was put to two distln- guished authorities. Undoubtedly said one, but the image would be too faint to be visible; the same screen exposed to the direct light of Mars, without the intervention of the telescope, would be illuminated fifty times more brightly. Certainly 1t is possible, replied the other, and it is equally possible to spread an acre of bread with one pat of butter.
 In truth, when M Deloncle proposed l to build for himself q telescope of fifty inches aperture, ten inches larger than | the largest existing refractor, he seems | to have had vastly exaggerated mo- | ton of the extra light-gathering uower | which that increase would give him. | It was not long before the more glaring | fallacies in his scheme were pointed out, but such warnings were swept aside in the wave of newspaper en- thusiasm which the catchword genera ted. The prospect of La lune un metre" fired the imagination, and a l syndicate was promoted to find the l money and build the telescope.
 Who it was that planned the instru- ment in the form in which 1t was con l structed does not appear. It Is a fixed | horizontal telescope, fed with light by | heliostat mirror; and 1t Is important | to note that, in the opinion of a great builder of telescopes, this will be of the form of the large telescopes of the fu- ture.
 The first very large instrument fash toned In this manner is built and stands waiting to be tried. It can cer- tainly never realize the exaggerated anticipations of its owners, but it might in a suitable climate, and prop erly handled, be of immense value It would be matter of the highest inter est to test it seriously against the best work of other instruments But It's builders seem to have no conception of any standard of excellence. Within q stone's throw of the observatory which is publishing a lunar atlas of marvel ous perfection they produce a few gro tesquely inferior results and shout, T have won the day"
 So long as the new telescope is run on these lines it will be doing no good at all and will have wasted a vast amount of money and skilled labor to no better purpose than to provide nine minutes wonder for the newspa- pers. M. Deloncle and his syndicate a snired tn render a great serVice tn