August 30, 1907] 



SCIENCE 



291 



precisely as pigmented individuals are, in re- 

 spect to tlie intensities of the pigments trans- 

 mitted, and even in respect to color-patterns 

 (spotting and the like). All that the albino 

 seems to lack in comparison with a pigmented 

 animal, is an activating substance, and even 

 this may be present in small amounts in the 

 albino, as, for example, in the Himalayan rab- 

 bit and in the similar variety of the albino 

 guinea-pig. My albino guinea-pigs of choco- 

 late parentage have brown-pigmented extremi- 

 ties, those of black parentage have black pig- 

 mented extremities. 



bibuography 



Bateson, W. 



1903. The present state of knowledge of colour- 

 heredity in mice and rats. Proe. Zool. Soc, 

 London, 1903, 2, pp. 71-99. 



Castle, W. E. 



1906. Yellow mice and gametic purity. Sci- 

 ence, N. S., Vol. XXIV., pp. 275-281. 



CU^NOT, L. 



1905. Les races pures et leurs combinaisons 

 chez les souris. Arch, de Zool. Exp. (4), torn. 

 3, notes et revue, pp. cxxiii-cxxxii. 

 Cumberland, C. 



. The guinea-pig, or domestic cavy, for 



food, fur and fancy. 100 pp., illus., London, 

 L. Upeott Gill. ' 



Davenpokt, C. B. 



1904. Color inheritance in mice. Science, N. 

 S., Vol. XIX., pp. 110-114. 



W. E. Castle 

 Zoologicai. Laboratory, 

 Harvard University, 

 August 8, 1907 



ASTRONOMICAL NOTES 



THE ASTROGRAPHIC CATALOGUE 



Volumes I. and II. of the Oxford Section 

 of the Astrographie Catalogue, by Herbert 

 Hall Turner, D.Sc, F.E.S., Savilian professor 

 of astronomy, have recently been issued. The 

 Oxford Section extends from Dec. -\- 24° to 

 4-32°. 



The International Congress on Astronom- 

 ical Photography met in Paris, in April, 1887. 

 Oxford was one of the eighteen observatories 

 which offered to take part in the mapping of 

 the heavens by means of photographs. Two 



schemes of work were planned, each to cover 

 the entire sky, one with short exposures of 

 6m, 3m and 20s, the other with exposures of 

 about one hour. Twenty years have elapsed 

 since that time. From Oxford we now have 

 the two volumes above referred to, which are 

 to be followed by six others. The whole bears 

 witness to the ability and energy of the author 

 and his assistants, and will no doubt prove of 

 great value to astronomy. It also illustrates 

 well the magnitude of the original schemes, 

 which appear to have been unwisely large, 

 since these eight volumes will complete only 

 the study of the plates of short exposure. 

 Professor Turner says: 



No attempt has, however, been made to take the 

 long-exposure series at Oxford, as there has never 

 been the least prospect of obtaining funds for 

 publishing the charts, either at Oxford or at the 

 majority of the participating observatories. 



Evidently some decades must yet elapse be- 

 fore the completion of the origiflal schemes, 

 even if the need for their completion should 

 remain urgent. 



The Oxford plates were made by an instru- 

 ment of the pattern proposed by the Henry 

 Brothers, of Paris. It has an object-glass of 

 13 inches aperture, and a focal length of Hi 

 feet, so that on the plates 1 mm. equals ap- 

 proximately 1'. The work was undertaken by 

 the late Professor Prichard, but his death, at 

 the advanced age of eighty-five years, took 

 place before much had been accomplished. 

 The catalogue gives the positions of the stars, 

 expressed in rectangular coordinates, and the 

 diameter of the stellar images, from which 

 the magnitudes may be derived. In many 

 cases it would be undesirable to use either of 

 these quantities in the form here given. 

 Tables are given, however, by means of which 

 the rectangular coordinates may be converted 

 into right ascensions and declinations. For 

 the conversion of diameters into magnitudes, 

 the formula is given: magnitude = a. — hVd, 

 where a and b are constants and d is the 

 diameter of the image. This formula, as 

 Professor Turner points out, introduces large 

 errors for the faint stars. The precision of 

 the positions is much more satisfactory, the 



