The Montgomery advertiser., 1903-12-13
ANOTHER TELESCOPE
DUPLICATE OF 24-INCH LENS FOR HAYWARD ASTRONOMERS

SS@ &A4&s 16O Aox10NS1A1%&A9 One will Be Used Near Boston and the Other to Be Sent to Arequipa Observatory. .- e
 Cambridge QGass.) Special to New York
 Times
 So successful has been the preliminary work with the new 24-inch Clark "mirroT' for the Harvard Astronomical observa- tory that a second and similar telescope has been ordered by that institution.
 One of these instruments will be set up at the Cambridge Observatory or at some other point near Boston. while the other will go to the Harvard station at Areaui- pa, Peru. there to take it's part in the sys- tematic study and photographic record of the sothern firmament-a work which par ailels and completes the iabors of the Cambridge Observatory.
 The new Arequipa telescope is interest ing. moreover. because It Is going to give practical opportunity to test side by slqe two telescopes of opposite character. For many years, 1t may be recalled. there have been controversies among astrono- mers regarding the respective merits of refracting and refiecting telescopes. A refractfng telescope Is similar to the lay mans spy-glass in construction-a long tube with convex lens at one end and an eye-piece at the other so that you look right through 1t directly at the stars. On the other hand a refiecting telescope. such as Harvard's mirror Is made for. re- verses the order of things. so to speak. for the observer gets up at the elevated end and looks down into a concave mir TOT, across the face of which the heaven iy bodies swim in their magnifed form. The new Harvard telescope will be of the refiecting type. having a mirror of carefully polished glass backed with sil- yer. When 1t is finished 1t will be set at Arequipa side by side with a refracting telescope of the same size and operat' d under the same general conditions. In such circumstances a comparison may easily be made. which. it is believed. will do more than merely satisfy scientific cu- riosity, since 1t will reveal definitely the respective value of these two important types of modern telescopes in certain diff ficult fields of astronomical research. During the past ten or twenty years there has been, 1t is said, a deci7ed reac- ton among astronomers in favor of the type of instrument just ordered by the Harvard Observatory and honored even by those who supported the claims of it's refracting rival, as the instrument used by the Herschels in making some of the greatest discoveries of astronomy. True it is that after Lord Ross had his giant telescope made the refracting type came into very general use. since the instru- ment is much easier to handle. There is an objection. however, in that one has to pay for this greater convenience by a loss of much of the light transmitted through the refracting lenses.
 Some twenty years ago Mir. Common, an English astronomer. attracted attention to the reflocting telescope by the admira- ble results which he obtained. Later a still larger reflector was made in Eng land. but nothing much was done with it until 1t passed into the hands of Prof. Keeler, of the Lick Observatory, who used 1t while making additions to our knowledge of the patches of distant stars known as nebulae.
 This work was continued after Prof. Keeler's death by his successor Prof. Campbell and by MT. Ritchey, of the Yerkes Observatory. who himself con structed large reflector with which he included star clusters and double stars as well as nebulae within the field of his investigations.
 Tn the mooted discussion of the value of the two types of instruments the work of these astronomers restored the reflect Ing telescope to position of great im- portance. but proved only. according to some astronomers. that the success lay, not in the instrument itself but in the skill of the man who used it. One advan- tage it certainly does have, and a most important one to the Harvard observa- tory. which has done so much in photo- graphing stellar spectra--its focus 10 un- varying for all colors. while that of tho refracting instrument differs considerably
 The refecting telescope in the opinion of these opponents, is a difficult piece oe apparatus to work with. even under the most favorable circumstances. The new vats~ the mirror. of course. Is the first and all- important consideration in any refle ting telescope-must be mounted in the most delicate manner. so that 1t Is a que5ti n whether it will finally be placed at the Observatory In Cambridge or somewhere else in he neighborhood.
 Electric cars. which often prove a hind rance to specific scientific work, pass close by the Observatory, and as the tremors started up as they pass. as well as the electric lights of a large city. may .nske 1t advisable to place the new Instruments a little further from Boston and from the possibility of such disturbances. At Are quipa, when the mirror just ordered has been completed. the trolley car problem Is naturally not likely to come up.
 It will probably be between two and three years before the mirror of the Are- quipa telescope is ready to start on its southern journey. for the manufacture of one of these important disks of glass Is a long, tedious and infinitely careful pro- cess.
 So delicate Is the operation that the fa- nous lensmaker, Alvan Clark, found only one young man whom he thought worthy to be apprenticed to his peculiar and. from the astronomical point of view, vi- tally important occupation.
 c. A. R. Ludin. who made-or 'hs- ured," if one wishes to be more technical the new Harvard mirror, is. therefore. a unique figure among modern workmen It was he also, although the last survivor of the Clark family lived until 1879. who did most of the work on the famous 4O- inch lens which has given the YeEkes Ob- servatory its present distinction of hay. ing the worlds largest piece of astronom- tcal apparatus.
 The finishing of such Q mirror as that just ordered by Harvard for her Arequipa Observatory. after 1t has gone through It's earlier processes. is a matter of about two years of hand labor, the maker hav- ing simply his thumb. a dish of water and bit of fine powder with which slow ly and carefully to grind down the ass to its final proportions. And this work which appears in the first statement ex- ceedingly simple. is complicated by a thousand and one difficulties known only to those familiar with this finest product of the telescope-maker's art
 Although the glass is mapufactured with consummate care in the one furnace in the world that is capable of producing 1t, that furnace being as far away from the lensmaker as the Louvre is from Har- yard University. nevertheless this glaes contains imperfectiona which must he