502 



NATURE 



[March 21, 1901 



presented by Mr. W. R. Temple ; a Pinche Monkey {Midas 

 aedipus) from Colombia, presented by Lady Moor; a West 

 African Python {Python sebae-natalensis) from Natal, presented 

 by Mr. Alex. Buchanan ; a Spotted Ichneumon {Herpestes auro- 

 punctatus), four Hamilton's Terrapins {Damonia hamiltoni), 

 seven Bungoma River Turtles {Eniyda granosa), eight Roofed 

 Terrapins {Kachuga tectum) from India, a Common Boa {Boa 

 constrictor) from South America, deposited ; a Maguari Stork 

 {Dissura maguari) from South America, four Gouldian Grass 

 Finches {Poephila gouldiae) from Australia, purchased. 



OUR ASTRONOMICAL COLUMN, 



Nova Persei.— Prof. H. C. Vogel describes, in the Astro- 

 nomtsche Nachrichten (Bd. 154, No. 3693), the results of 

 measures of photographs of the spectrum of Nova Persei, taken 

 with the 80 cm. refractor and spectrograph of small dispersion. 

 The spectra extend from \ 3740 to X 5800. Wave-lengths have 

 been determined by comparisons with the spectrum of ;3 Orionis 

 (Rigel). Tables of the wave-lengths of the deduced lines are 

 given, the origins being traced to hydrogen, calcium, magnesium 

 and silicon. The displacements of the lines is shown to indi- 

 cate a velocity of some 700 kilometres per second relative to 

 the earth ; an exception to this occurs in the case of the two 

 calcium lines at H and K, which are indicated as giving velocities 

 of approach of only 45 kilometres per second. 



Variability of Eros. — At the Lyons Observatory MM. 

 Guillaume, Le Cadet and Luizet have recently obtained a series 

 of estimations of the variations in the brightness of Eros, ob- 

 serving with an equatorial coude of o 32 metre aperture and a 

 Brunner equatorial, 0'i6 metre aperture. A diagram of the light 

 curve is givn. This is similar to that of j8 Lyrse, but the 

 secondary minimum is almost equal to the principal one. The 

 determinations gave 



h. m. 

 Principal minimum to secondary minimum = 251 

 Secondary ,, principal ,, = 2 24 



Principal maximum to secondary maximum = 2 50 



Details of estimates on seven nights during February are 

 given {Comptes rendus, cxxxii. pp. 530-531). 



In the same issue M. Luizet gives the elements for computing 

 future minima as follows : — 



h. m. h. m. 



1901 Feb. 20. ... 7 57I , .- T- 

 20. ... 10 48) + 5 I6-I5E. 



The eccentricity of the orbit of the system would thus be 

 about 0'0569, which is nearly equal to that of the moon's orbit 

 (0-0549). 



In the current issue of the Comptes rendus, M. L. Montan- 

 gerand describes the photographic investigations which have 

 been made with the astrographic refractor at the Toulouse Ob- 

 servatory. It is inieresting to note that the measures so obtained 

 agree very well wiih visual determinations. The planet was 

 allowed to trail over the plate, and the points of equal bright- 

 ness marked off at intervals. The period thus found is given 

 as 2h. 38m. (2h. -63) {Comptes rendus, cxxxii. pp. 616-618). 



In close agreement with this result is the determination of 

 Prof. Deichmiiller at Bonn, who gives 2h. "61 as the period of 

 variation. This observer gives also, for the two evenings of 

 February 21 and 22, a series of estimations of magnitude at 

 intervals of ten minutes from 5*0 to lO'O p.m. {Astronomische 

 Nachrichten, Bd. 154, No. 3693). 



New Variable, 2 1901 (Cygni).— Dr. T. D. Anderson 

 announces, in the Asti onomische Nachrichten (Bd. 154, No. 

 3692), the discovery of a new variable star. Its position is 

 h. m. 

 R.A. = 19 I2'2'\ , 0-- \ 



Decl. = +49° 55' )^'^55-o). 

 And the variations recorded are 



1900 Dec. 26 ... 9 '5 



1901 Jan. 12 ... 98 

 Feb. 16 ... io'4 



Observations of Circumpolar Variable Stars.— 

 Vol. xxxvii. part i of the Annals oiW^^ Harvard College Obser. 



NO. l63», VOL. 63] 



vatory conlains the results and discussion of the observations of 

 17 circumpolar variables made at the institution during the 

 period 1889- 1899. The estimates of magnitude were made by 

 Argelander's method, but differ from similar observations of 

 other workers in two respects — first, the stars have been observed 

 throughout the whole period of their variation of light ; and 

 second, all the observations have been reduced to a uniform 

 photometric scale, that of the meridian photometer'. This latter 

 peculiarity is of great importance, as by its means the stars can 

 not only be systematically compared inter se, but collateral com- 

 parisons made with stars of constant brightness in any part of 

 the sky. Both the 15 inch and 6-inch equatorials have been 

 employed in the work. 



Three of the stars, T Persei, S Persei and R Ursse Minoris 

 appear to be irregularly variable. With the exception of these, 

 mean light curves have been deduced for the variables, and 

 tables are given showing the phases obtained by this means. 

 An examination of the curves shows that the principal maximum 

 is in several cases preceded, and in a few cases followed, by 

 a more or less marked secondary maximum. 



Treating these variables as a class, it is noted that the 



mean of all the periods ... = 363 '4 days 



mean magnitude at maximum = 7'8i 

 ,, ,, ,, minimum = I2'64 



So that the range is therefore = 4-83 magnitudes. 



Drawings are given of the mean light curves of 14 of the 

 variables, and 16 small charts showing their positions with respect 

 to the surrounding stars. 



EROS AND THE SOLAR PARALLAX. 



T^EW projects involving long continued observation and labo- 

 -^ rious calculations have received a more ready assent or 

 commanded a wider co-operation than that which has for its aim 

 the determination of the solar parallax from observations of the 

 planet Eros. This readiness to adopt a general programme 

 was materially assisted by the meeting of the International Astro- 

 photographic Congress at Paris, in July 1900, whereby the 

 directors of many of the best equipped observatories were able 

 to rapidly mature their plans and to complete the necessary 

 organisation. The representatives of some twenty observatories 

 gave in their adhesion to the proposal, which contemplates the 

 collection of measures, either photographic, micrometrical or 

 heliometric, and the necessary meridian observation of a large 

 number of comparison stars. The general scheme follows the 

 well-known lines of utilising observations made at considerable 

 hour angles east and west of the meridian at any one observatory, 

 of combining the observations made in the north and south 

 hemispheres, and adds the somewhat novel feature of making 

 available simultaneous observations of the planet at stations in 

 America and Europe, a suggestion which, among other advan- 

 tages, has the effect of eliminating errors arising from an im- 

 perfect knowledge of the planet's motion. 



Under date, Paris, January 31, M. Loewy gives an interim 

 report of the progress of the observations up to the end of the 

 year 1900. M. Loewy and those responsible for the inception 

 of the scheme are to be congratulated on the energy exhibited 

 and the hopeful results obtained. The report states that, not- 

 withstanding the bad weather that has generally prevailed in 

 the northern regions of our hemisphere, not one day has passed 

 in which the planet has not been observed by one or other of 

 the several methods adopted. The number of coincidences of 

 observation between the three contributing American observa- 

 tories and those in Europe is shown by the following figures : — 



Number of Coincidences up to December 31, 19CO. 



Madison. Washington. Williams Bay Total. 

 (Verkes). 

 Micrometric ... 40 ... 49 ... 106 ... 195 



Photographic ... 15 ... 30 ... 66 ... m 



The English observatories of Oxford and Cambridge (Green- 

 wich is not reported) are in the least favourable position, since 

 the arc of the Great Circle intercepted between them and the 

 average American station is only about 55° ; but seeing that 

 the parallax of the sun can be determined quite independently 

 of the motion of the planet, and that the stars of comparison 

 will be the same in the two cases, a very small error can be 

 anticipated under the least favourable conditions. Considerable 

 attention has been given to the amount of this error, and one 



