278 



SCIENCE. 



[Vol. VII., No. 164 



of the Murghab. To the north-west both rivers 

 are lost in the sands of the desert. The Hari-Rud 

 is crossed by a bridge ninety-seven yards long. 

 From this point it was formerly a distance of 

 ninety kilometres to the nearest fresh water, but 

 this has been diminished to forty-eight kilometres 

 by a canal constructed by Colonel Alikhanoff dur- 

 ing the past season. This diverts part of the 

 water of the Murghab, but it was found im- 

 practicable to extend it further. The latter river, 

 unlike the Hari-Rud, does not dry up, but carries 

 in winter seventy-five cubic metres per second 

 as against three hundred in summer. It contains 

 about two per cent of earthy matter, amounting, 

 for the annual epoch of floods, to about fifty 

 million cubic metres of mud, which is spread by 

 the innumerable irrigating canals over the surface 

 of the Merv oasis. The destruction in 1784, of the 

 great dike of Sultan Bend, much diminished the 

 irrigated and fertile area. The Russian govern- 

 ment has reserved sixty thousand rubles to re- 

 build this dike, and it is expected that nearly four 

 hundred thousand acres will be reclaimed by this 

 work, and, in time, nearly four times as much 

 more. This land, when irrigated, is of extreme 

 fertility, w r heat producing a crop of one hundred 

 bushels for every bushel sown. Merv is growing 

 rapidly : town lots of a certain size are given 

 away, on condition that the receiver builds upon 

 them at once. The streets are wide, with broad 

 foot walks, planted with trees, and bordered with 

 small canals. The oasis is confidently expected to 

 develop largely in the near future. 



PHOTOGRAPHIC STUDY OF STELLAR 

 SPECTRA. 



The study of stellar spectra by means of pho- 

 tography was one of the most important investiga- 

 tions undertaken by the late Prof. Henry Draper. 

 He was actively engaged in this research during 

 the last years of his life. His plans included an 

 extensive investigation, one object of which was to 

 catalogue and classify the stars by their spectra. 

 Mrs. Draper has made provision, at the observatory 

 of Harvard college, for continuing these researches 

 as a memorial to her husband. The results al- 

 ready obtained, with the aid of an appropriation 

 from the Bache fund, permit the form of the 

 new investigation to be definitely stated. The 

 part of the sky to be surveyed is that extending 

 from the north pole to the parallel of thirty de- 

 grees south declination. Each photograph will be 

 exposed for about one hour, and will include a 

 region ten degrees square. The telescope em- 

 ployed has an aperture of twenty centimetres 

 (eight inches), and a focal length of a hundred 



and seventeen centimetres (forty-four inches). The 

 object-glass is covered by a prism, and the result- 

 ing spectrum of each star in the region photo- 

 graphed has a length of about one centimetre, 

 which enables the character of the spectra of stars 

 from the fifth to the eighth magnitude to be 

 determined. A modification of the apparatus is 

 employed for the brighter stars. 



Meanwhile, experiments are in progress with 

 the fifteen-inch equatorial, with the object of 

 representing the spectra of some typical stars upon 

 a large scale. The spectra so far obtained are 

 about six centimetres in length, and exhibit much 

 well-defined detail. Additional experiments will 

 be tried with a spectroscope provided with a slit, 

 as well as with the simple prism hitherto em- 

 ployed, in order to secure the best possible 

 definition. The present results encourage the 

 expectation that the movements of stars in the 

 line of sight may be better determined by the 

 photographic method than by direct observations. 



To keep the astronomical public informed of the 

 progress made in this work, specimens of the 

 photographs obtained will be gratuitously dis- 

 tributed from time to time. The first of these 

 distributions will probably be made in a few 

 weeks. Owing to the expense of providing a large 

 number of copies, it is desirable to limit the dis- 

 tribution, so far as possible, to those who are inter- 

 ested in this class of work. It is also desired, 

 however, to send the specimens to all who will 

 find them of value from the scientific point of 

 view. Requests should be sent to the Harvard 

 college observatory by any one desirous of receiv- 

 ing the specimens. Edward C. Pickering. 



THE HUDSON BAY ROUTE TO EUROPE. 



Last year there appeared in Science (vol. v. No. 

 110) an account of the Hudson Bay expedition of 

 1884, accompanied by a track-chart showing the 

 route followed. Lieutenant Gordon's official re- 

 port of his last summer's trip to the bay, to 

 relieve the observers at the stations established 

 in the strait in 1884, is included in the annual 

 report of the Canadian department of marine, 

 lately submitted to the Dominion parliament. It 

 is in narrative form, and contains little new in- 

 formation, the results of the observations con- 

 ducted at the several stations being reserved for 

 publication as a separate report so soon as they 

 shall have been reduced to proper form. 



Lieutenant Gordon, after promising details of 

 the observations at an early date, concludes his 

 report with the following remarks on the pros- 

 pects of navigating the strait : " The reports go to 

 show that the ice set fast in the western end of 



