XOVEMBEE 1, 1894. 



KNOWLEDGE 



253 



I 



STRUCTURE OF THE MILKY WAY. 



By Prof. E. E. Barnabd and A. C. Eany.\ed. 



SEND to Knowledge a pbotograpli which I have 

 recently made with the 6-iiich Willard leus. The 

 picture is in i r-u i -„ 



S = -2.3°, 



and was made -luly 6th, 9h. 30m. — 13h. om., 1894, 

 Standard Pacific time. 



This picture shows the remarkable structure of that 

 portion of the Milky AVay near 5 Ophiuchi — the large star 

 near the middle of the plate. This is a very obscure 

 region to the naked eye, made especially so by the great 

 olouds to the east and south-east of it. It is essentially a 

 region of vacancies. There is a great chasm here in the 

 Milky Way which sweeps from the east of 6 Ophiuchi, 

 under it south, and then westward. Theta itself is in a 

 region of stars and nebulosity. I would, however, question 

 this nebulosity, as it may be only areas of very small stars. 

 There are two peculiar narrow, interrupted vacancies run- 

 ning north and south on each side of 5 ; the westei-n of 

 these passes quite close to the star. About 2° north of 5 

 is a singular small S-shaped vacancy, which is a very 

 remarkable and striking object. 



It wiU be noticed that in many of these vacancies there 

 are "deeper depths" yet, which almost suggest that the 

 appearance of diifused nebulosity over the region is real 

 nebulosity, and that these dark and black places in it are 

 thin places and actual holes. 



This picture, taken in connection with Mr. Wesley's 

 interesting paper in August Exowledge, will give much 

 food for thought and speculation. I have no doubt Mr. 

 Pianyard will be able to discuss this photograph in his 

 usual thorough style, so I shall leave it with these brief 

 references. 



Mount Hamilton, August 20th, 1894. 



[The dark vacant areas or channels running north and 

 south, in the neighbourhood of the bright star at the centre 

 of the picture referred to by Prof. Barnard, seem to me to 

 be undoubtedly dark structures, or absorbing masses in 

 space, which cut out the light from a nebulous or steUar 

 region behind them. On the glass positive sent by Prof. 

 Barnard several of such dark areas or dark channels are 

 recognizable in different parts of the photograph. There 

 are three nearly parallel dark channels to the east of 

 9 Ophiuchi, which throw out curving branches on either 

 side, which are well shown in oin- plate. They appear to 

 nie to spring from the great dark chasm or rift which 

 sweeps from the east of 3 Ophiuchi to the south, and then 

 under it to the westward. It seems to me that these dark 

 structures most probably spring from the great rift, because 

 the lateral branches all diverge in a direction away from 

 the rift, and there is a resemblance in thek spreading 

 heads to the. forms which solar prominences assume as 

 the outrushing matter from the sun expands and suffers 

 resistance from the medium into which it is projected. 

 Several smaller dark channels may be traced diverging 

 from different parts of the great rift ; one from near its 

 western end stretches downwards into a very comphcated 

 head, with diverging narrow branches. 



It is comparatively easy to conceive of a narrow stream 

 of dark nebulosity or foggy matter cutting out the light of 

 a uniform background ; while if the narrow dark regions 

 correspond to thin places or holes in the nebulosity, they 



must be holes or thin places extending in a direction away 

 from the earth. The probabilities against such a radial 

 arrangement with respect to the earths place in space seem 

 to my mind to conclusively prove that the narrow dark 

 spaces are due to streams of absorbing matter, rather than 

 to holes or thin regions in bright nebulosity. — A. C. 



R.VXYARD.^ 



Sfitnrc Notts. 



Mr. Richard Inwards delivered an interesting presidential 

 address to the Meteorological Society on " Some Pheno- 

 mena of the Upper Air." He described the experimental 

 balloons which have been sent up in France by M. Hermitf, 

 carrying instruments so contrived as to register the various 

 changes of condition through which the balloon passes. 

 The results are most instructive. It appears that one of 

 these balloons rose to a height of ten miles, when the 

 pressure of the air was only 4-1 inches of mercury and the 

 temperature — 104^ F. Though there are considerable 

 variations in the temperature gradient below twelve thou- 

 sand feet above the sea level, it seems that above that 

 height the temperature decreases pretty regularly, falling 

 one degree for every rise of three hundred and thirty feet 

 into the air. 



Our cup of tea hitherto has come to us as an unquestion- 

 able oriental, a thing unique in the flavour of the far East 

 that it brings with it. But soon, it seems, all that will be 

 changed, for America has discovered that she can grow 

 tea as good if not better than that of India or China. 

 Through private enterprise, aided by the Government, tea, 

 reported by experts to be of very fine quality, has been 

 most successfully grown at Pinehurst, near Charleston, 

 U.S.A., and there seems to be no reason why its coltivation 

 should not quickly become general in many districts. 



In the chemistry section of the British Association, 

 Prof. H. B. Dixon, in his opening address, gave an 

 entertaining historical account of Oxford chemistry. After 

 Boyle left in 1668, the impulse he had given to its study 

 gradually died out. In 1683 we are informed that "the 

 Oxford elaboratory was quite finished." In 1708 Eichard 

 Frewin is described as being Professor of Chemistry there. 

 Uffenbach, after a visit to Oxford about that time, says he 

 found the stoves in fair condition, but everything else in 

 the "elaboratory" was in dirt and disorder. Frewin 

 must have been a man of great facility, for in 1727 he was 

 elected Camden Professor of Ancient History. Whether 

 he stiU looked after the elaboratory, or whether it went 

 professorless, is not stated. At all events, Frewin must 

 have been a conscientious man in his way, in spite of that 

 suggestive fact about the stoves, for on his election to the 

 chair of History he seems to have made a genuine attempt 

 to become familiar with the new subject, and we are told 

 that he at once expended one hundred pounds in books on 

 chronology and history to fit himself for his duties. The 

 occupation of the chair of Chemistry seems in those days to 

 have been mere by-play in the career of a man. Eichard 

 Watson, who ultimately became Bishop of Llandaff, was in 

 1764 appointed Professor of Chemistry at Cambridge. We 

 are told that he knew nothing at all of chemistry ; he had 

 never read a syllable nor seen an experiment. So on his 

 election he sent in a hurry to Paris for an " operator," and 

 set to work in his laboratory. Clearly in those days there 

 could not have been quite so much to learn as now, for 

 fourteen months after we find him lecturing to a large 

 audience. 



