September 8, 1898 J 



NA TURE 



463 



OUR ASTRONOMICAL COLUMN. 



A Large Sun-spot. — On Saturday last a very fine spot was 

 visible near the sun's eastern limb, having evidently been 

 brought into view by the sun's rotation. Its full magnitude 

 was revealed a few days later, when the foreshortening was 

 reduced. Changes in the umbra and bright bridges crossing 

 it were detected in the course of a few hours. The spot will 

 be well worth watching during the remaining period of its 

 visibility, especially as many years may perhaps elapse before 

 observers are favoured with another spot of similar size. 



The Atmosphere of D.M. + 30" 3639.— Prof. Keeler 

 announces, in the Astrophysical Journal for August, that he has 

 fully confirmed Prof. Campbell's discovery of a hydrogen 

 envelope around the Wolf-Rayet star D. M. + 30° 3639 (Nature, 

 vol. xlix. p. 210). The observation was made with the spectro- 

 scope attached to the 36-inch refractor of the Lick Observatory, 

 and it was found that the 1 1/3 line appeared as a circular fairly 

 well-defined disc when the slit was opened wide, the cylindrical 

 lens being of course removed, and the focus correctly adjusted 

 on the slit plate for light of that wave-length. No such appear- 

 ance was noticed in the case of the line at 4652, which has 

 almost the same brightness as H/s, thus proving that the disc 

 was not due to irradiation. Further proof that the appearance 

 was not an illusion was afforded by the visibility of the H 

 line when the star itself was thrown off the slit, as in the ob- 

 servation of the solar chromosphere. Prof. Keeler believes 

 that this hydrogen envelope could be observed visually with a 

 large reflector without the aid of a spectroscope, a piece of 

 lilue glass, perhaps, being] required. With a refractor the disc 

 would be confused with the circles of chromatic aberration. 



The Exterior Nebulosities of the Pleiades. — In con- 

 nection with the recent discussion concerning the real exist- 

 ence of certain nebulous patches depicted on photographs of 

 the Pleiades taken with a portrait lens, Prof. Barnard has 

 forwarded to the editors of the Observatory a copy of a photo- 

 graph of the same region taken by Dr. H. C, Wilson. This 

 picture was obtained with a 6-inch Brashear portrait lens, the 

 exposure being eleven hours. The coincidence in position of 

 the patches on two perfectly independent photographs is con- 

 sidered strong evidence of their actual existence. The whole 

 group of stars in the Pleiades would thus appear to be in- 

 volved in scattered nebulosity, with the brightest portions in 

 the neighbourhood of some of the brighter stars. 



Luminosity of Gases in Vacuum Tubes,— Bolometric 

 measurements made by K. Angstrom have indicated that the 

 radiation of a gas rendered luminous by electricity is proportional 

 to the current strength, within the wide limits of his experiments. 

 This relation was equally true for the total and luminous radia- 

 tion, and it might be expected that the same law would hold 

 good for the luminosity of the separate spectral lines. In the 

 Physical Review for July, E. S. Ferry details the results of a 

 photometric study of the changes produced in the spectra of 

 pure gases when suh)jected to various conditions of current and 

 pressure. An accumulator of twelve hundred elements was 

 employed to render luminous the gas in the discharge tube, 

 experience having shown that the use of a Ruhmkorff coil pro- 

 duces composite spectral lines whose luminosity is influenced by 

 the partial discharges which follow each principal discharge of 

 the secondary coil. The line spectrum of hydrogen and the 

 band spectrum of nitrogen were investigated, and the following 

 conclusion sarrived at : (i) With gas pressure from 0-25 mm. 

 to 4"oo mm. of mercury, and current strengths from i milli- 

 ampere to 6 milliamperes, the luminosity of the separate 

 spectral lines of gases at a given pressure is directly proportional 

 to the current strength. (2) With constant current, the 

 luminosity of a spectral line of a gas increases as the pressure 

 decreases, at first slowly and then more rapidly. The curve 

 showing the relation between the pressure of the gas and the 

 luminosity of a spectral line is regular, but is different for 

 different lines. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



On the initiative of the Business Committee of the Glasgow 

 University General Council, a movement has been set on foot 

 to place a stained glass window in the Bute Hall of the Uni- 

 versity as a special tribute by past and present students of the 



NO. 1506, VOL. 58] 



University of Glasgow to ihe memory of the late Prof. Caird. 

 It is estimated that the undertaking will require about 1000/., 

 and the maximum subscription is i/. \s. As there are many 

 former students of the University whom it is obviously impossible 

 to communicate with from any lists at present available, the 

 co-operation of all interested in making the movement known 

 among students of older date is invited. The Secretaries are 

 Mr. John G. Kerr, Convener of the Business Committee of the 

 University General Council, and the Rev. Arthur Stanley 

 Middleton, President of the Students' Representative Council. 

 Mr. Archibald Craig, 156 St. Vincent Street, Glasgow, is 

 Treasurer. 



Readers of prospectuses of educational institutions and 

 polytechnics may have noticed that of late years there has been 

 a tendency to convert the teachers into professors. The nature 

 of the institution in which the instructors can rightly use the 

 latter title is apparently a matter of opinion, and it is becoming 

 worth while to define the duties and position of a professor. 

 Miss Catherine Dodd describes in the National Kevte-v how she 

 asked 105 primary school children, between the ages of ten and 

 fourteen, to give this definition, among others. Here are some 

 of the attempts : — " A man who has passed a high examination." 

 "Avery clever man." "One who can do his work easily." 

 " A man skilled in sense." That a professor has a certain social 

 standing is evident from the definitions which describe him as 

 "a man who is well off," and "a man who lives in a nice 

 house." Among the vague definitions are the following : — " A 

 person who professes to do something." " A man who says he 

 can do anything." But the children's general idea is that a 

 professor teaches music, dancing, or languages, or performs 

 conjuring tricks. Thus, " A professor teaches all kinds of instru- 

 ments." "He is a gentleman that generally plays at balls,'* 

 and "a man who knows clever tricks." To correctly define a. 

 professor would probably prove a difficulty to many children of 

 older growth. 



In April of the present year the New York State Legislature 

 passed an Act authorising the trustees of Cornell University 

 "to create and establish a department in said University to be 

 known as, and called, the New York State College of Forestry, 

 for the purpose of education and instruction in the principles 

 and practices of scientific forestry." In the same Act, provision, 

 was also made to establish a Demonstration Forest of not more 

 than 30,000 acres in the Adirondacks, to be purchased out of 

 the funds set aside for the Forest Preserve Board, and to become 

 the property of Cornell University for the term of thirty years, and 

 to be used for demonstrations of practical forestry. The sum of 

 10,000 dollars has been granted for the organisation and 

 maintenance of the College and Demonstration Forest. A copy 

 of the prospectus of this new institution, the director of which 

 is Prof. B. E. Fernow, has just been received, and it shows that 

 the College will furnish systematic instruction in the science 

 and art of forestry. Scientific forestry has not hitherto received 

 much attention in the United States, so the new College should 

 prove of assistance not only to New York State, but to the. 

 whole country, by increasing and extending the knowledge of 

 rational methods of forest management. As the College is ir>- 

 connection with Cornell University, the educational facilities fon 

 the studies leading to the degree of Bachelor of the Science ot 

 Forestry are of the best ; while the large College Forest in the 

 Adirondacks furnishes opportunities for studying practically, 

 methods of silviculture and forest administration. Each student 

 as a part of his last year's work will be required to write a 

 thesis, selected with the advice of the director, giving the 

 results of a personal investigation upon some forestry subject. 

 The opportunities for study and investigation in all branches of 

 the natural sciences underlying forestry and in the various 

 departments of Cornell University are ample, while the con- 

 nection of the demonstration area with the College of Forestry 

 will furnish additional advantage for original work, research 

 and experimentation, in advancing the science and art of 

 forestry. Some time must elapse before the College Forest i» 

 in the best shape for demonstrative purposes, but starting under 

 such high auspices, there is every promise that the institutioa. 

 will prove a success. 



Introductory addresses will be given at many of the. 

 metropolitan and provincial medical schools, at the opening of 

 the winter session early in October. At St. George's Hospital 

 (says the Tinus) the session will begin on October i, with an 

 introductory address by Mr. G. R. Turner, surgeon to tho- 



