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SCIENCE 



[N. S. Vol. XXIX. No. 734 



cometary matter such as are shown in the photo- 

 graphs of Morehouse's comet on October 15, etc. 



4. Sixty spectrograms of this Algol-type variable 

 were obtained at the Allegheny Observatory dur- 

 ing this year. These indicate a nearly circular 

 orbit with a range of 146 kilometers per second. 

 The center of gravity of the system is approaching 

 us at the high rate of 46 kilometers per second. 

 The light curves of this variable has been the 

 subject of a recent exhaustive investigation by 

 Kron. A study of the results obtained by him, 

 and of the spectrographic data, enables us to infer 

 the following with regard to the constitution of 

 the system, upon the assumption that the light 

 changes are caused by an eclipse. The two stars 

 in, the system have nearly equal diameters (about 

 two and a half that of the sun), but one of them 

 is nine times as bright as the other. Their av- 

 erage separation is about one thirtieth of that 

 between the earth and the sun. If we assume that 

 the two stars are equally dense the mass of each 

 would be about six tenths and the density about 

 one twenty-fifth that of the sun. 



In discussing a series of measurements made 

 two years ago upon ^ Persei, Professor Schlesinger 

 showed that in the case of this star there is a 

 discrepancy between the phase demanded respect- 

 ively by the light and velocity changes. Further 

 investigation has confirmed the reality of this 

 discrepancy and has shown that it can not be 

 accounted for by any uncertainties in either the 

 photometric or spectrographic data. It is inter- 

 esting to notice that the same discrepancy is 

 present in the orbit of 8 LibrcB. In this case the 

 light phase lags more than two hours behind the 

 velocity phase. The discrepancy is, therefore, 

 somewhat greater than in the case of p Persei, 

 but it is in the same direction. 



5. Professor Updegraff gave the following ac- 

 count of the six-inch transit circle of the U. S. 

 Naval Observatory: 



This instrument was acquired by the Naval 

 Observatory with a view to its employment in 

 doing fundamental work. The nine-inch brass 

 transit circle made by Pistor and Martins, of 

 Berlin, and mounted in the old Naval Observatory 

 in 1865 was considered unsuitable for fundamental 

 work of the highest class, and after the removal 

 of the observatory to the new site on Georgetown 

 Heights about the year 1893, the new six-inch 

 steel transit circle was designed by Professor Wm. 

 Harkness and was built by the well-known instru- 

 ment makers, Warner & Swasey, of Cleveland, 

 Ohio. The instrument was mounted in the west 

 transit circle house at the new Naval Observatory 



in December, 1897, and was first brought into use 

 in June, 1899. A description of the six-inch tran- 

 sit circle may be found in volume III., Part 4, 

 of the Publications of the Naval Observatory, 

 together with an account of the work done with 

 it up to March, 1901. 



The design of the instrument is substantially 

 the same as that of the later Repsold meridian 

 circles, and certain features have been the subject 

 of considerable controversy. It was, I think, the 

 first large instrument of this kind to be built of 

 steel, which being a much stiffer metal than brass 

 is expected to diminish errors due to flexures. 

 This feature has been much criticized, but the 

 example set by Professor Harkness has been fol- 

 lowed by the Repsolds in making the new transit 

 circle for the observatory at Kiel, Germany, which 

 is also of steel, and the prospect is that steel or 

 some other rigid metal will finally be recognized 

 as preferable to brass for the construction of large 

 instruments of this kind. 



When brought into use the new instrument was 

 found to have various defects, the most important 

 of which, an extraordinary variability in azimuth, 

 was found to be intimately connected with tem- 

 perature. After a very troublesome investigation 

 this was found to be due to two causes. The 

 cast-steel bed plates which supported the instru- 

 ment were, through non-homogeneity of the metal, 

 distorted by temperature changes, and the marble 

 piers of the instrument were not properly sup- 

 ported on their foundations. New bed plates of 

 east iron were provided, and the marble piers of 

 the instrument were replaced by brick piers. 

 These measures gave relief, and rendered the in- 

 strument remarkably stable in azimuth. 



A peculiar but not serious difficulty has arisen 

 from the construction of the tube of the telescope 

 of steel. In a brass telescope of moderate size the 

 changes in focal length of the object glass with 

 temperature is nearly the same as the expansion 

 and contraction of the tube with changes of tem- 

 perature. But the coefficient of expansion of steel 

 is smaller than that of brass, and in the case of 

 the tube of the six-inch transit circle is not suffi- 

 cient to make up for the change of focus of the 

 object-glass. This makes necessary a change of 

 stellar focus from winter to summer and vice 

 versa. 



In the fall of 1901 the instrument had been put 

 in good condition, and for about one year follow- 

 ing was employed in observations of the fixed 

 stars and also in observations of the sun, moon 

 and planets. The latter work with the instrument 

 was continued up to September, 1903, when work 



