372 



K^•o^^'LED^IE. 



September, 1911. 



kiniinosity : three of them would be more than one hundred 

 times as bright as the Sun at its distance ; six between fifty 

 and one hundred times as bright : twenty-two between ten 

 and fifty times ; and the faintest of the forty-one stars has 

 five times the luminosity of the Sun. Out of the fourteen 

 stars in a group, which have been examined with the spectro- 

 scope, eight have proved to be binaries. It is probable that 

 quite a number ififty) of fainter stars also belong to the 

 cluster : but their Proper Motions are not as yet sufficiently 

 well determined to be certain." 



It is not too much to say that considering the care and 

 exactitude with which they have been constructed these two 

 models are unique. 



There are exhibited in the .Astronomy Section a large 

 collection of photographs and transparencies contributed by 

 the Observatories of Greenwich. Cambridge. Stonyhurst and 

 the Cape, the Royal .Astronomical Society and others. 

 .Among the most interesting is a very beautiful series of 

 transparencies contributed by M. Deslandres, from the 

 Meudon Observatory. These comprise some thirty spectro- 

 heliograms of the Sun in calcium and hydrogen light, showing 

 the most recent and remarkable results obtained at that 

 Observatory. 



To understand the great advance that has been made in this 

 branch of solar research in the last few years, it should be 

 borne in mind that up to the year 1908, spectroheliograms of 

 the Sun's surface were obtained with instruments of such 

 moderate dispersion that the radiations from several layers in 

 the solar atmosphere were integrated. As the lower layers 

 are the more brilliant, the forms of the upper regions were 

 more or less masked. The construction of a more powerful 

 instrument at Meudon, has enabled M. Deslandres to satis- 

 factorily isolate the light of the upper atmosphere from 

 that of the lower strata. The results can be very well 

 studied in the photographs exhibited. Numerous examples 

 are shown taken in pure KJ light — the highest layer 



in the Sun's atmosphere yet examined. These are new. and 

 the credit of obtaining them belongs to M. Deslandres. Com- 

 paring these with those taken in K2-3 light it is found they 

 possess characteristics which distinguish them clearly from the 

 lower layers. Striking examples are shown of the curious 

 black markings called "filaments." and the connection of these 

 filaments with S(jlar prominences. Equally striking is the fact 

 noted by M. Deslandres, that some of these filaments seem to 

 form a zone round the poles. The photographs taken in 

 hydrogen light are eijually worthy of study. They show 

 remarkable difl'erences, according as the}' are taken with the 

 centre or the borders of the Ha line. 



Interesting photographs are exhibited taken uith the 

 '■ Spectroenregistreur des vitesses," that is, a spectro-helio- 

 graph of Velocities, which photographs the displacements of 

 the spectrum lines in the line of sight for all points on the 

 solar disc. The study of the results obtained with this new 

 method of M. Deslandres shows that vapours are rising over 

 the areas represented by the dark filaments, and descending 

 over the areas represented by the bright faculae. Space does 

 not allow of our giving a more detailed account of this exhibit 

 which is deserving of close study. 



The late M. Charles Emile Stuyvaert, of the Royal Observa- 

 tory, Brussels, devoted the last ten years of his life to the 

 construction, in wax, of a model of the moon which was 

 almost completed at the time of his death in 1908. The model 

 was made on a scale of one-millionth the natural size. One 

 portion of it representing the Lunar craters Arzachel and 

 Alpetragius is shown at the exhibition, and is one of a series of 

 twenty-four similar models which represented the complete 

 hemisphere. 



(jn the whole, the science of .Astronomy is fairly well 

 represented at the Exhibition, not only in the list of those 

 who have sent contributions, but from the fact that the 

 exhiliits may be considered in many respects as indicating 

 the most recent adv.inces in the science. 



NUTICKS. 



NOTES OF A NATURALIST IN THE MEDITER- 

 RANE.AN. — Mr. G. B. Hony asks us to point out that the 

 date which was given in .the August number for the 

 appearance of Nightingales at Granada as March 10th should 

 be May 10th. 



A UNIgCE SUNDIAL.~Mr. J. A. Hardcastle writes to 

 say that at his request Colonel \V. (i. .Armstrong some time 

 ago described a similar sundial to that of which Mr. A. Paul 

 Monckton gave an account in the August number, in The 

 Journal of the British Astronomical Association, and 

 that Miss .Agues Fry has pointed out that there is one 

 depicted in Holbein's picture of "The Ambassadors" in the 

 National Gallery. 



APPARATUS FOR ELECTRO - THERAPY AND 

 DIAGNOSIS. — Messrs. W. Watson and Sons' new catalogue 

 dealing with these subjects runs into nearly one hundred pages. 

 Besides containing illustrations of all the most up-to-date coils 

 and X-Ray tubes, screens and radiometers, it shows some 

 interesting pictures of an improved intensifier screen called 

 the '" Sunic " for X-Ray work, by which the exposures are 

 reduced by ninety-five per cent. The saving in the life of the 

 tubes quickly repays the cost of the screen. The figure 

 showing sciagraphs of a hand taken with an exposure of one 

 twentieth of a second on a plate of which half only was 

 covered with the screen, is very remarkable. 



THE FEKY REFRACTOMETER.— We h.ise pleasure 

 in announcing that Messrs. Adam Hilger, Limited, have intro- 

 duced M. Fery's Refractometer and have issued a descriptive 

 pamphlet with regard to this instrument which is a direct read- 

 ing refractometer for taking the refractive index, for sodium 

 light, of oils, solutions of acids, sugar solutions, mixtures of 

 glycerine, alcohols and so on with water. 



AN IMPROVEMENT IN THE MICROSCOPE STAND. 

 — Messrs. R. .S;. J. Beck have introduced an improvement in 

 the shape of the stands of many of their microscopes which 

 allows the limb of the microscope between the fine adjustment 

 screw and the stage, to be grasped by the whole hand so that 

 when the instrument is lifted none of the adjustments are 

 altered. The same firm has put upon the market a grinding 

 and polishing machine of a most compact nature for the pur- 

 pose of making microscopical specimens for metallurgical 

 work. 



PRISM BINOCULARS.— Mr. E. Leitz sends usan illustrated 

 list of his prismatic binoculars, which includes several new 

 patterns. At one end of the series is an instrument giving 

 a magnification of four diameters, which is used in the theatre 

 while at the other end is a field-glass giving three times this 

 magnification. There is a new glass also with a magnification 

 of eight, which has an enlarged field of view and an improved 

 stereoscopic effect. The latter is obtained by increasing the 

 distance between the object glasses relatively to that between 

 the eye pieces, and this, particularly at the range at which a 

 student of natural history would require to use the glass, 

 certainly assists vision. 



MICROSCOPES AND ACCESSORIklS.— Section one. 

 Part one, of Mr. C. Baker's catalogue deals with the microscopes 

 made by his well-known firm. Among special microscopes 

 are the inexpensive ones designed for nature students and 

 meat inspectors, while we may also mention the diagnostic 

 microscope for the use of officers in foreign medical service 

 for the diagnosis of malarial fever. .A very similar model has 

 also been designed for the use of travellers. 



Parts two, three and four of the same catalogue are occupied 

 by dissecting instruments, stains, mounted specimens for sale 

 or hire and apparatus for collecting pond life. 



