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Show eionssii mm-was mm-was Director of Mount Wilson Observatory Reports on Measurement VA9AUV.SK CmI.. Jan. 1 (Hy Aim-elated Aim-elated I'mil. I)r. George Kllery Hale, director of Ihe Mt. Wilson oh. eervatnry, near here, glrrk to the Associated As-sociated Pres. an artlrl. he bad written writ-ten describing the aureesaful measuring measur-ing at the nhservalnry. Ierrmter IS. of the etar Hetelee;eue, in the constellation con-stellation of Orion, allowing Its diameter diame-ter to he 100.000.oft0 miles. Ir. Hale's letter follows: "On iJecember ta, 19J0, the diameter of the bright red str Beteleireuia Arable for "the slant's shoulder In lha rmi.lnllall,.. r.t flrltin, .nf. eessftilly measured on Mt. Wilson. "The stars are so remote that hitherto hith-erto It haa not been possible to measure meas-ure their diameter. In spite of the fart that many stars must be much larger lhn the suiT "In his presidential eddrees 1t August before the Mrltleh Association for the Advancement of He ie nee. Prof. A. K. f'.dillngton. the wll known aa-trnnomee aa-trnnomee of the University of Cambridge, Cam-bridge, remarked: MIST 0R8AT NEED. 'Probably the irrentest need of stellar astronomy at the present day. In order to make sure that our theoretical theo-retical deductions are starting on the right lines, la some knowledge of measuring the apparent angular diameter diam-eter of stars.' "He then went on to predict that Mhe atar with the greatest apparent diameter Is almoat certainly Tletel-geuse, Tletel-geuse, diameter fi.wftl seconds of arc.' "The result fust obtained Is a remarkable re-markable verification of thla prediction predic-tion "The measurement was made with the 100-inch Hnked telescope hr Messrs. Pease and Anderson of the observatory ntntt, "No telescope Is powerful enough to measure accurately the extremely mall ana-le subtended hv a star. Thfs verv difficult and delicate tnek la rendered possible by a method devised by Professor- Michelsnn. director of tha Ryerson phvsfr"! laboratory of the t'nlveraltv of Chicago, snd research re-search asuocmte of the Mt. Wilson observatory and of the California Institute In-stitute of Technology. ROUGHLY DESCRIBED. "While thla method Is too technics) to h clearly explained In a short article. ar-ticle. It may be auld that It I. based upon the phenomenon known aa the Interference of light. "The special Instrument devised hy Professor Michelson for ths application applica-tion of the method Is, therefore, called sn Interferometer' and a verr large Instrument nf this kind twenty feet In lenrth was built In the observatory instrument ahnp. "Purlng Professor Mlchelsnn's visit to Mt. filsnc last summer this Interferometer Inter-ferometer wrs attached, to the tipper end of the tube of Ihe lOO-lnch tele-scone tele-scone anil successfully adjusted and Te.fed: " "After further tests and Improve, ments It haa not been applied to Ihe measurement of Itetelgeuxe "The measti'ed angular dlnmeter t II (Uf seconds of sre. In rurprMnrly close agreement with Profeesor dlngtnn's calculation. While this Is a preliminary value which will be Improved Im-proved hy siihscrjitent messures. it Is probably correct within 10 per cent. METHOD PURSUED. "To lesrn the linear diameter of the stur we ui know (ta rilmance from the earth. The three available measures meas-ures of the distance of netelgeuie nre jot In very close agrecmciiLJuit the sverage I. probably fairly relinble.i t'alng thla vnlue the diameter of the star comes out three million mllea. In oiher words. It would fill the orhit of Mars! "The colossal aixe of Betelgeuse will be recognised) when It la compared with the sun. which Is less thun a million miles In dl.-imeter. The sun. If It were a hollow sphere, would contain con-tain a million hodiee aa large as the earth, or. if the earth were fixed, at It. center, the moon. Jto.OAO mites awav. could mors In It. orbit and have much room to apare. Tet when we remember that the sun In a state of very attenuated ga. many millions of years ago, must have filled the entire eolar svstem. we recognise the possibility Ihst stars even larger than lletelgetise msy exist. CONFIRMS CONCLUSIONS. "The new result beautifully confirms con-firms the recent conclusions of Kus-sell. Kus-sell. Hertsaprung and other students of stellar evolution. A few years (so Russell showed that there must be two great classes of stars: the 'giants.' huge gaseous bodies In an early stsge of development, and the 'dwarfs.' which have condensed to the stage represented) hr our mm and many ?elltw and red) stars srhosa life histories histo-ries are at HI mora advanced. The validity of Hun sell's views has been bnrn out hy tha Inveatfi-sttons nf Ir. Adams and his associates an Mt. Wileon. through the um of Adams Ad-ams new and remarkable method of measuring the distance and Intrinsic brightness of stars with tha spectro scf'ne. "Tha successful measurement of the dlamater of a stellar 'riant' now fur mshea tho last link In tha chain and fre pares the way fop a promising . er-tenamn er-tenamn of our Invest Ism tlona on the J formation and development of thai stars.- |