Lapas attēli
PDF
ePub

Repeated object lessons have demonstrated that nearly all progress in science has resulted in important advances in industry

[graphic]
[ocr errors]

G-E Research Laboratory

Schenectady, N. Y.

Among the many products developed by the General
Electric Company's research laboratories the following
are of special interest to manufacturers:

[blocks in formation]

For further information address Supply Department, Schenectady Office.

General Electric

Company

[graphic]

General Office
Schenectady. N.Y.

Sales Offices in all large cities

35B-48

HELBER COUNTING

COUNTING CHAMBER

FOR USE IN BACTERIOLOGICAL WORK IN THE STANDARDIZATION

OF VACCINES BY THE COUNTING METHOD

[merged small][merged small][merged small][graphic][graphic][subsumed][subsumed][subsumed][subsumed][subsumed][merged small][merged small]

The Helber Counting Chamber was originally designed for the counting of blood platelettes, but is now widely used in bacteriological work in the control of bacterial vaccines by the counting method. This counting chamber is made in the same shop and by the same workmen as the Levy Counting Chamber for blood counting and embodies all the advantages of precise workmanship, legibility of rulings and accuracy of dimensions for which the Levy Counting Chamber has become justly famous. It is provided with the Neubauer ruling exactly as used for blood counting with the exception that the depth of the chamber is 0.02 mm. instead of 0.1 mm. This extremely shallow chamber is difficult to manufacture and for satisfactory results requires the use of special cover glass such as No. 30006 Hausser Reinforced Precision Cover Glass.

The Hausner Reinforced Precision Cover Glass is suitable for use with any counting chamber but is specially made for use on the Helber chamber in bacteriological work where its extreme thinness, 0.18 mm., permits the use of a 1.9 mm. homogeneous immersion objective with the ruling of the Helber chamber in sharp focus a procedure impossible with the ordinary counting chamber with its cell depth of 0.1 mm. and the usual cover glass of 0.4 mm. thickness, as the sum total of these dimensions exceeds the free working distance of such high power objectives. The reinforcement greatly increases the rigidity and durability of the cover glass and decreases the otherwise unavoidable breakage in the handling of such thin cover glasses without reinforcement. The beveled slide of the reinforcement permits ready cleaning and also convenient observation of the front of the microscope objective when brought into close approximation to the upper surface of the cover glass for the purpose of engaging the oil. The under surface of this glass is guaranteed plane to within 0.002 mm. 30038. Helber Counting Chamber, as above described, with one No. 30006 Hausser

reinforced precision cover glass 0.18 mm. thick, but without case........ 14.00 30037. ditto, but tested by the Bureau of Standards and engraved with official mark of certification on both counting chamber and cover glass.....

18.00 30006. Hausser Reinforced Precision Cover Glass, as above described, 20 x 26 mm., with transparent area 12 x 12 mm.; 0.18 mm. thick....

2.00 30007. ditto, but tested by the Bureau of Standards and engraved with official mark of certification...

2.25

Pricos subject to change without notice

ARTHUR H. THOMAS COMPANY

WHOLESALE, RETAIL AND EXPORT MERCHANTS LABORATORY APPARATUS AND REAGENTS WEST WASHINGTON SQUARE

PHILADELPHIA, U, S. A.

SCIENCE

[blocks in formation]

SHERBURNE WESLEY BURNHAM,

1838-1921 We record, with deep regret at his passing, but with high appreciation of his long and valuable service to astronomical science, the death of Sherburne Wesley Burnham, emeritus professor of practical astronomy at the Yerkes Observatory, of the University of Chicago.

Born on December 12, 1838, in the upper valley of the Connecticut, at Thetford, Vermont, Mr. Burnham had the ordinary advantages of the district school, supplemented by some study in the local academy, but he did not go to college. He became an expert stenographer and shorthand reporter, long before the days of the typewriter, and this was his profession for some thirty years. During the Civil War he served in his professional capacity with the Union Army while it was occupying the city of New Orleans. He came to Chicago, after the close of the war, and became attached to the United States Courts.

His interest in astronomy must have developed very early in the sixties, for he purchased his first telescope during a visit to London in 1861; and in 1870 he became the possessor of a fine six-inch refractor, a masterpiece of Alvan Clark, which he had ordered in 1869. Mr. Burnham's vision was extraordinarily keen, for among the 451 new double stars which he discovered with that instrument many were found by other observers to be extremely difficult to resolve with much larger instruments.

In 1873 and 1874 he sent five lists of new double stars to the Royal Astronomical Society, which were published in the Monthly Notices. At first he had no micrometer, and was obliged to give estimated angles and distances. A correspondence developed with Baron Ercole Dembowski, who gladly made

[blocks in formation]

the micrometric measurements, with his ex- duced the principle of using the telescope for cellent skill, using a refractor of 162 mm. all it was worth while the sky permitted: in aperture at Gallarate, in Italy. Two lists other words, no part of the night when the covering 136 new double stars were printed sky was clear was given up for any bodily in the Astronomische Nachrichten in 1875 and weariness of the observer. In 1892, owing to 1876. A short list followed in the American certain conditions at Mt. Hamilton which Journal of Science in 1877 and in Monthly were unacceptable to Mr. Burnham, he reNotices for the same year. In 1879 his new turned to Chicago, where he was offered the doubles from Nos. 483 to 733 were published highly responsible position of Clerk of the in the forty-fourth volume of the Memoirs of United States Circuit Court. Incidentally he the Royal Astronomical Society, together with was receiver of the Chicago and Northern micrometric measures of 250 other stars. Pacific Railroad Company from 1897 to 1902.

During the years from 1877 to 1881 and Mr. Burnham was in charge of the expedi1882 to 1884, Mr. Burnham had the use of tion from Lick Observatory to observe, at the splendid 184 inch Clark refractor of the Cayenne, the solar eclipse of December 21–22, Dearborn Observatory, then set up in the 1889. Good results were secured, due in no tower attached to the old Chicago University. small measure to Mr. Burnham's large ex

In 1879 he was requested by the trustees perience in photography. The report was of the Lick Trust to test the conditions on written by Burnham and his associate, Mr. Mt. Hamilton. He took his 6-inch refractor, Schaeberle, and published in 1891 in a small now equipped with circles and a driving volume from the Lick Observatory. clock, to Mt. Hamilton and made observa- On the inauguration of the Yerkes Obtions from August 17 to October 16. His servatory in 1897, Burnham became an active highly favorable report settled the choice of member of the staff, making his observations Mt. Hamilton as the site for the Lick Ob- throughout the nights of Saturday and Sunservatory. In 1881 he went again to Mt. day and returning to his duties in the court Hamilton, by request, and observed the transit on Monday morning. In 1902 he resigned his of Mercury with the 12-inch telescope. position with the court, despite the life tenure

During some six months of 1881 he was of that office. This gave him more time for astronomer, under E. S. Holden, at the Uni- his astronomical studies, but he still retained versity of Wisconsin, where the 15.5-inch his residence in Chicago, coming to Williams telescope of the Washburn Observatory had Bay for observations on two nights in the recently been erected. While there he dis- week. He became Professor emeritus in 1914, covered and measured 88 new double stars; at the age of 75, the statute of the University and he measured a large number of double of Chicago requiring retirement at 70 having stars Selected from his MS. General Cata- thus far been waived in his case. Although logue of Double Stars, as specially needing the opportunity for using the 40-inch teleobservation." These observations appeared in scope still remained open to him as before, Vol. I. of the Publications of the Washburn he hardly availed himself of it, and his last Observatory in 1882. Mr. Burnham's famous observations here were made on May 13, 1914. 6-inch refractor ultimately become a part of Vol. II. of the Publications of the Lick the equipment at Madison.

Observatory contain his observations from On the inauguration of the Lick Observa- August, 1888, to June, 1892, and his fourtory in 1888, with Professor Holden tenth to nineteenth catalogues of new double director, Mr. Burnham received the appoint- stars discovered at the Lick Observatory in ment as astronomer, and thus had abundant that period, including the numbers from opportunities for the use of the great 36-inch B 1026 to B 1274. The search for new doubles Clark refractor for the continuance of his was made chiefly with the excellent 12-inch work. At the Lick Observatory he intro- telescope. He also found some new nebulæ,

as

and measured the positions of numerous says of it that “very few will fully appreciate planetary nebulæ which are given in the same the enormous amount of hard work which has volume. His orbits for several of the more been necessarily expended in the preparation interesting systems on which he had been of such a work. . . . It should be remarked in working appear at the end of that volume. It this connection that with the exception of will be seen that Mr. Burnham had largely the four years from 1898 to 1902 all this given up the search for new double stars astronomical work, with the telescope and while at the Lick Observatory, regarding it otherwise, has been done when eight or more as more important that accurate observations hours of at least six days in the week were should be made of the systems already dis- very much occupied with other and different covered, particularly those for which large affairs of life.” After his retirement from instruments were necessary.

active observations, Mr. Burnham turned this Vol. I. of the Publications of the Yerkes MS. catalogue and the responsibility of its Observatory, issued in 1900, is entitled “A up-keep over to Professor Eric Doolittle, General Catalogue of 1290 Double Stars Dis- whose premature death in 1920 is much covered from 1871 to 1899 by S. W. Burn- lamented. From him, by prior arrangement, ham.” It gives in order of right ascension this passed on to Professor Robert G. Aitken, the history of all of the Burnham stars up to of the Lick Observatory, who thus carries on B No. 1290. Aside from his own observa- the work which will eventually result in a tions, it summarizes the results of all other new edition of the “ General Catalogue of All observers of these stars and gives diagrams Double Stars," now to be mentioned. Efforts and orbits, by the author and others, of had been made for many years to have this several interesting systems. He did not allow great work published, but it could not be himself to be distracted from his specialty brought about until the Carnegie Institution by the allurements of other fields of obser- of Washington in 1905 undertook to publish vation: it was seldom that he loɔked at it. The composition was done with great care nebulæ unless there were double stars to be by the University of Chicago Press, and measured therein; and he had no time for Part I. was published before the close of 1906. observing comets, however interesting. It lists 13,665 double stars and summarizes made an exception in locating Halley's comet the numerical information about them, in a on September 15, 1909, two nights after it quarto volume of 275 pages. Part II., of had been first caught on a photographic plate 1,086 pages, gives details of all important obby Wolf at Heidelberg: thus Burnham's eye servations of the pairs, with many diagrams. was the first to see the comet, then an ex- It constitutes a magnum opus of which any tremely faint speck, on this return to peri- scientist could be justly proud. helion.

With the 40-inch telescope of the Yerkes During the beginning of Mr. Burnham's Observatory, Mr. Burnham gave no time to use of the 6-inch telescope, he felt the great the discovery of new doubles. In fact, he need of a single catalogue of all double stars avoided them, if possible, and occasionally in the Northern Hemisphere and he therefore mentioned seeing some which he did not arranged a manuscript catalogue of all known record. In recent years he took a good deal double stars within 121° of the north pole. of interest in the determination of the proper This was conveniently indexed and proved of motions of the brighter stars by micrometricgreat service to the observer. He revised it ally connecting them with neighboring faint in two MS. editions, the third of which stars, for which a negligible proper motion allowed ample room for expansion and is still could be assumed. This work was largely to in use. The preparation of this catalogue had lay the foundation for a greatly increased entailed a great amount of labor, as it was knowledge of proper motion in the future. Mr. constantly kept up to date. Mr. Burnham Burnham realized very fully the great advan

« iepriekšējāTurpināt »