May 2, 1889] 



NATURE 



17 



to 'the south; it is from 4000 to 4600 feet above sea-level. 

 Nearly the whole of it is magnificently watered by a net- 

 work of running stream?, the springs supplying which well out 

 from the highest portions of the downs, so that an enormous 

 area of land could be put under irrigation. The whole year 

 round a cool wind blows almost continuously from the south-east, 

 a wind which in the winter months becomes so cold that it may 

 well have its origin among the icebergs of the Antarctic sea>. 

 The country, Mr. Selous assures us from his own experience, is 

 admirably adapted for European occupation and labour. The 

 soil is rich and fertile, and from the facilities for irrigation 

 enormous quantities of wheat could be grown. Although the 

 highest and healthiest parts of the country are very open, still 

 one is never out of sight of patches of trees. Be^ides the high 

 plateau of Mashonaland, the whole of which is over 4000 feet 

 above sea-level, extending along the watershed for a distance of 

 over 200 miles from the Matabele country to the source of the 

 Hanyane and Mazoe Rivers, with a breadth of from sixty to one 

 hundred miles, there is a vast extent of country lying to the south, 

 east, and north-east of the plateau, well-watered and fertile, 

 having an altitude of from 3000 to 4000 feet. These plateaus 

 are of much ethnological interest, as giving shelter to the very 

 few remnants of the peaceful Mashonas that have escaped 

 extermination at the hands of the bloodthirsty intruders, the 

 Matabele. 



Mr. Selous leaves England for the Cape to-morrow. It is 

 possible that he may be compelled to lead a prospecting party 

 up .the Zambesi. Should this not be the case, he is likely to 

 proceed northwards bevond the Zambesi to the Garenganze 

 country, west of Lake Bangweolo, and thence make either for 

 the source of the Lualaba, which he will endeavour to follow 

 down until it broadens out into the Congo. 



M. J. Taupin, Professor in the College of Interpreteis at 

 Saigon, has completed an important exploration in the lower Laos 

 cotintry. Starting from Saigon in October 1887, M. Taupin, after 

 visiting the Siamese province of Siem-Reap, and photographing 

 the numerous Khmer remains in that province, notably those of 

 Angkor, crossed the forests of the lower Laos, to Ubon, where 

 he resided several months. Among other things he has obtained 

 a knowledge, at least summary, of the Laotian language and 

 writing, the only graphic-alphabetic system, it is stated, on which 

 we have no positive information. The language, M. Taupin 

 states, is spoken by four million people. He has surveyed about 

 looo kilometres of rivers and watercourses not found on any 

 map, besides making many important corrections. He has made 

 many notes on natural history, and experimented with the culture 

 of European plants. The meteorology and anthropology of the 

 country, moreover, received much attention at his hands. 



At the next meeting of the Geographical Society, on May 13, 

 the evening will be mainly occupied with a discussion of Mr. 

 Stanley's letters, in which several well-known African authorities 

 are likely to take part. 



Captain Binger, a French explorer, has succeeded in filling 

 up one of the blanks on the map of Africa. Starting from the 

 banks of the Niger, he penetrated the country of Kong, amid 

 many dangers and sufferings. 



THE HENRY DRAPER MEMORIAL.^ 

 nr HE researches which constitute the Henry Draper Memorial 

 have consisted for the last three years in the photographic 

 study of the spectra of the stars. While this subject will con- 

 tinue to be the principal one under investigation, Mrs. Draper 

 has decided to extend the field of work undertaken, so as to 

 include the study of the other physical properties of the stars by 

 photography. As will be seen from the detailed statement 

 below, the first research undertaken is now rapidly approaching 

 completion, the plans for the study of the bouthern stars have 

 been matured, and this study will soon be begun ; the detailed 

 study of the spectra of the brighter stars is making progress, and 

 a large piece of photometric work will soon be undertaken with 

 a new telescope. The progress made in each investigation will 

 now be described, as in previous Reports. 



I. Catalogue of Spectra of Bright Stars. — The Bache tele- 

 scope, which has an 8-inch photographic doublet as an objective, 

 is used for this work. The photographs cover the entire sky 



^ " Third Annual Report of the Photographic .Study of Stellar Spectr.i 

 conducted at the Harvard College Observatory," Edward C. Pickering, 

 Director. (Cambridge : John Wilson and Son, University Press i88j.) 



north of -25°, with exposures of about five or ten minutes. 

 About 28,000 spectra of 10,800 stars have been examined, in- 

 cluding nearly all stars visible in Cambridge of the seventh 

 magnitude or brighter. The Catalogue is now nearly ready for the 

 printer, the final copy having been prepared as far as I4h. in right 

 ascension. 



Nearly the entire time of three or four computers has been 

 devoted during the past year to this work. The intensity of 

 about 15,000 of the spectra has been measured, completing this 

 part of the research. Much lime has been spent in checking and 

 verifying the results. All the positions have been checked and 

 brought forward to 1900 two or more times independently. All 

 discordant measures have been re-examined, and a search has 

 been made for possible error when bright stars are omitted or 

 very faint ones inserted. Seven thousand two hundred notes 

 have been made on the various stars in the Catalogue. Each 

 note has an appropriate number which permits it to be entered 

 in its proper place. Most of these notes relate to additional lines 

 contained in these spectra besides those by which the type is 

 determined. The position and intensity of these lines is 

 estimated. A portion of them have been reduced to wave- 

 lengths. The printing of the Catalogue might have been already 

 begun but for the difficulty of deciding how the different types 

 of spectra should be distinguished. The classification used for 

 visual observations fails to indicate many differences obvious in 

 the photographs. On the other hand, the photographic portions 

 of spectra of Types H. and HL are nearly identical. The photo- 

 graphs also show many stars whose spectra are intermediate 

 between those of the typical stars which have determined the 

 usual classification. A system has, however, been adopted 

 which permits all differences detected in the photographs to be 

 described in the printed volume. 



Thirteen spectra were found on these plates which could not 

 be identified with stars. Three of these proved to be due to 

 Mars, one to Vesta, three to Jupiter, four to Saturn, and two to 

 Uranus. Accordingly all the exterior planets bright enough to 

 be detected in this way appear on these plates. 



The measures of the intensity of the spectra form a very 

 important portion of this work. Since the same part of the 

 spectrum is measured in each case, the true relative energy is 

 determined. That is, the same result is obtained as if the 

 measures of rays of the same wave-length were made by any 

 other method, as photometrically by the eye, by the thermopile, 

 or by the bolometer. The colour of the star will be indicated 

 by the extent of the spectrum, which is also noted. For the 

 first time, therefore, we shall have a photometric Catalogue in 

 which the error due to the colour of the star is eliminated. A 

 preliminary determination of the accordance of the results de- 

 rived from different photographs of the same star shows that the 

 average value of the residuals will be about o'l6, which is the 

 same as the corresponding quantity for the Harvard Photometry. 

 The number of stars is more than twice that contained in the 

 latter Catalogue. 



2. Catalogue of Spectra of Faint Stars.— li\ November 1888, 

 the photographs required to cover the sky north of the equator 

 were nearly finished. It was expected that in two months the 

 observations would be completed. The telescope, which was 

 the same as that used in the previous research, was, however, 

 wanted for photographing the Solar Eclipse of January I, 1889. 

 It was accordingly sent to Willows, California, where it was 

 mounted, and the greater portion of the remaining photographs 

 were taken there, it was then sent to Peru, as will be described 

 below. The few remaining photographs, including the repeti- 

 tion of those found on further examination to be unsatisfactory, 

 will be taken in Peru. 



3. Detailed Study of the Spectra of the Brighter Stars.— T\\q 

 1 1 -inch refractor with one, two, or four large prisms over its 

 objective h^s been employed in this work throughout nearly 

 every clear night, until stopped by the morning twilight ; 686 

 photographs have been taken, mo.-.t of them with an exposure of 

 two hours. With cur prestnt photographic plates about 570 

 stars north of -30° are bright enough to be photographed with 

 one prism, 170 of them with two prisms, and 87 of them with 

 four prisms. To obtain the best possible result some of the 

 photographs must be repeated many limes. The difficulty is 

 increased by the invariably hazy appearance of the lines in 

 some spectra, like that of o Aquiia;, which was at first attributed 

 to poor definition of the photograph. It is expected that the 

 work will be completed during the next year by original or 

 repeated photographs of 228 stars with one prism, of 64 with 

 two, and of 12 with four. In general, stars as bright as the 



