354 



SCIENCE. 



[N. S. Vol. XXIV. No. 612. 



words within the walls of the physical 

 laboratory. It is here only possible briefly 

 to refer to the labors of a few of those 

 distinguished seekers after natural knowl- 

 edge. 



The work of Dr. Sprengel has been by 

 no means an unimportant factor in the 

 .advance of our knowledge of radiant en- 

 ergy, X-rays, etc., if only on account of 

 the perfection of the apparatus for obtain- 

 ing high vacua which will ever be associ- 

 >ated with his name. The practical effect 

 ■of his discoveries was considerable, for the 

 l3usiness of electric lighting is undoubtedly 

 greatly indebted to his labors. Born in 

 1834, he settled in England at the age of 

 twenty-five. He was elected a fellow of 

 the Eoyal Society in 1878, and resided in 

 this country during the remaining years of 

 his life. 



The death of Charles Jasper Joly, 

 P.R.S., at the early age of forty-one, 

 robbed mathematics and astronomy of one 

 of their most devoted disciples. His 

 * Manual of Quaternions' is well known, 

 and those acquainted with his astronomical 

 w^ork are confident that, had his life been 

 spared, he would, as astronomer royal of 

 Ireland, have added luster to an office held 

 by many distinguished predecessors. 



Samuel Pierpont Langley was born in 

 1834. In 1866 he became director of the 

 Allegheny Observatory at Pittsburg. His 

 first work was the institution of a uniform 

 system of time from the Atlantic seaboard 

 to the Great Lakes. This, the first success- 

 ful attempt to introduce uniformity of 

 time over a large area, was subsequently 

 widely imitated. In 1880 he invented the 

 bolometer, and thus opened out a large new 

 field of investigation into the invisible rays 

 of long wave-length proceeding from heat- 

 ■ed bodies. He analyzed in minute detail 

 the lunar heat spectrum, and, more recent- 

 ly, he conducted an inquiry into the nature 



of the radiations emitted by the glow- 

 worm. In 1881 he conducted his researches 

 into the solar heat of the earth's atmos- 

 phere. In 1887 he became secretary to 

 the Smithsonian Institution. The result 

 of twenty years' labor is to be found in the 

 accurate determination, by temperature 

 alone, of more than seven hundred lines 

 in the invisible red spectrum, lines which 

 are fixed with an average probable error 

 of about one second of arc. In 1891 he 

 published his experiments in aerodynamics, 

 in 1893 'The Internal Work of the Wind' 

 and in 1896 he demonstrated by actual ex- 

 periment that a body nearly a thousand 

 times heavier than air can be driven 

 through and sustained by it. His pub- 

 lished works show great literary charm. 

 Pie especially excelled in the presentation 

 of abstruse subjects in simple and non- 

 technical language. This is, perhaps, 

 hardly the occasion to refer to his social 

 qualities. Those who had the privilege of 

 his acquaintance, however, can best testify 

 to his quickness of insight, his intense sym- 

 pathy, especially with the young, and the 

 impression of capability which he produced 

 upon all with whom he came in contact. 



The tragic death of Professor Curie was 

 felt as a calamity, not only by those closely 

 interested in the march of scientific dis- 

 covery, but also by those who had but a 

 superficial knowledge of his work. A 

 teacher for more than twenty years, he was, 

 nevertheless, enabled by his enthusiasm and 

 energy to perform those researches which 

 will ever be connected with his name and 

 that of his wife. So entirely has public 

 attention been attracted to their joint work 

 on the separation of the compounds of 

 radium and their properties that we are 

 apt to overlook other great services he ren- 

 dered to science. His paper on 'The Effect 

 of Temperature on the Magnetic Proper- 

 ties of Bodies' led to the discovery of the 



