566 



NATURE 



[February 22, 191 2 



instruments and experimenting on the best methods of 

 observation. A thorough test of the new Brashear doublet 

 for stellar photography has been made by Hartmann's 

 zonal method, and comparison photographs with different 

 adjustments are given in illustration of the method. 



Other work in this division included micrometric 

 measurements of double stars, comet photographs, star 

 occultations, solar photography, and adjustment of the new 

 large grating spectrograph and ca>lostat. 



The ccelostat telescope is of the form installed by Hale 

 at Mount Wil.son, known as the Snow telescope, consisting 

 of a plane mirror ccelostat with secondary mirror, concave 

 image mirror, and Littrow spectrograph with plane diffrac- 

 tion grating. 'Jhe main ccelostat mirror, 20 inches 

 diameter, driven by clockwork, reflects the sunlight in a 

 southerly direction to a secondary plane mirror, which in 

 turn reflects the light northwards to a concave mirror, 

 18 inches diameter. This forms an image of the sun 

 slightly less than 9 inches diameter on the slit plate of 



View of the Ottawa ccelostat, looking north. A, main coelostat mirror ; 

 B, secondary ccelostat mirror ; C, concave image mirror. 



the spectrograph, fixed in the basement of the main build- 

 ing of the observatory. This arrangement of mirrors is 

 clearly shown in the accompanying illustration, taken from 

 the report. The whole is covered by a louvred structure, 

 part of which can be moved to allow of the sunlight reach- 

 ing the coelostat mirror at all seasons. 



The large solar spectrograph is located in the basement, 

 and consists of a 6-inch lens of 22 feet 10 inches focal 

 length, together with a Michelson plane diffraction grating 

 mounted in the Littrow form. The whole instrument is 

 mounted so as to be capable of rotation about the collima- 

 tion axis, this making it possible to place the slit tangential 

 to any required point on the sun's limb. 



•Some interesting photographs of comet Morehouse are 

 given showing the varying appearance presented by the 

 tail during October and November, 1908. 



Geophysics. — In the geophysical division reports are 

 presented showing the progress of determinations of 

 seismology, terrestrial magnetism, gravity measurements, 

 and latitude and longitude work on numerous stations 

 throughout the Dominion. Charles P. Bl'tler. 



NO. 2208, VOL. 881 



THE PRECIPITIN REACTION. 



''PHE precipitin reaction is also known as the " biological 

 reaction" for proteins; it enables us to distingui-! 

 between proteins by using the animal body as a test-tt:' 

 and to establish differences between them which no oth< : 

 form of test-tulw; will detect. It is best known as a 

 means for distinguishing human from other forms of blood. 

 The procedure is briefly to inject an animal (usually a 

 rabbit) repeatedly with a foreign protein ; the serum of that 

 animal then gives a precipitate with that protein, ^ut with 

 no other. So if the material injected is human blood, a 

 precipitate is produced when the serum of the blood of th<- 

 rabbit is added to human blood, or at any rate to the 

 blood of the group of animals (the higher apes) to wh'ch 

 man belongs, but not with any other sort of blood. The 

 reaction is of value in forensic medicine, and it is also of 

 value to the zoologist, as it enables him to demonstrate 

 the blood-relationships of animals, and by the amount of 

 precipitate to ascertain the degree of the relationship in 

 figures. 



A vast amount of research has centred around this dis- 

 covery, Bordet, Uhlenhuth, Tchistowitch, and Nuttall 

 being a few among the many who have devoted themselves 

 to working out its details. A very clear and concise 

 account of the principal facts has been recently published 

 in a lecture given by Dr. W. A. Schmidt before the Cairo 

 Scientific Society {Cairo Scientific Journal, November. 

 191 1). Dr. Schmidt's name is known as one of those 

 who have within recent years examined Egyptian 

 mummies by chemical means, and his publications on the 

 precipitin reaction have also been important. His lecture 

 naturally deals with the question in a general and popular 

 way, but includes a reference to some of his own work. 



.Among other interesting points. Dr. Schmidt has deter- 

 mined is the resistance of proteins to heat. It wa> 

 formerly supposed that the " biological " property of 

 proteins was easily destroyed by an elevated temperature, 

 liut Schmidt has shown that boiling for half an hour is 

 iif ( essary to abolish their power of reacting with a pre- 

 cipitin serum ; and even although this is accomplished, the 

 heated protein still retains the power when injected into an 

 animal of inducing the formation of a precipitin whicli 

 reacts with heated or boiled protein material. Further 

 than this, protein may still be further " denaturalised " 

 and retain a corresponding power ; when, for instance, 

 protein is coagulated by a high temperature, so that 

 ordinary neutral reagents no longer dissolve it, a solu- 

 tion of it in dilute alkali will produce precipitin-formation 

 in the blood of an injected animal, which will react only 

 with the " denaturalised " protein used for the injection. 

 This discovery extends the usefulness of the precipitin 

 reaction, for with the precautions described by Dr. Schmidt 

 it may be employed to detect proteins even though some of 

 their principal chemical properties have been destroyed. 



5(7/-;\ 7 //•/(• Ml.MiUUAJ. VOI.l'MK. CELE- 



BR.VnOS OF THE 500TH ASM\ ERSARY. 



UNIVERSITY OF ST. ANDREWS. 



A NE.ATLV bound memorial volume of scientific papers 

 ■^ was issued by the University of St. Andrews to 

 mark, with other publications, its 500th anniversary last 

 September, and is edited by Profs. Mcintosh, Steggall, and 

 Irvine. The first paper, on concrete representations of non- 

 Euclidean geometry, by an able mathematician. Dr. 

 D. M. V. Somerville, consists of a description of the most 

 important representations which have been devised for 

 non-Euclidean geometry within the field of ordinary 

 Euclidean geometry, viz. : — (i) the Cayley-Klein projective 

 metric, or representation by straight lines referred to a 

 conic as absolute ; (2) the conform representation by circles 

 orthogonal to a fixed circle; (3) Beltrami's geodesic repre- 

 sentation on surfaces of constant curvature ; (4) McClintock 

 and Johnson's representation by "visual geometry": 

 (5) the representation by a net of conies through two fixed 

 points ; and (6) Poincar^'s representation by diametral 

 sections of a quadric surface. 



The second paper is on the algebraic solution of in- 

 determinate cubic equations, by Mr. Robert Norrie. The 

 third, by Prof. Peddie, treats of the problem of partition 



