8o 



SCIENCE. 



by this Time Service, the signals of which reach Bangor, 

 Lennoxville, in Canada, Albany, and New York, as well as 

 different points in Massachusetts. The copper time-ball, 

 held by a powerful electro-magnet at the top of the mast 

 on the Equitable Life Assurance Building, Boston, is re- 

 leased at noon by the clock at Cambridge. During 1879 

 accidents caused a small error in its fall on two days only, 

 and on three days it has been dropped at I2h. 5 ~\ os. 



The great equatorial of fifteen inches' aperture and the 

 meridian circle whose telescope has an aperture of eight 

 inches have been kept actively in use for the last three 

 yrars. The former instrument has been devoted almost 

 entirely to photometric work. The problem of astronomi- 

 cal photometry, roughly stated, is to determine the bright- 

 ness of all the heavenly bodies, so that all may be compared 

 with a single standard. Previous to the beginning of this 

 work at the Harvard Observatory, photometric measure- 

 ments had been made almost entirely upon the planets and 

 brighter stars, and there was no definite knowledge of the 

 amount of light emitted by the satellites and fainter stars. 

 At the outset of the work several hundred measurements 

 were taken of the brightness of the outer and inner satel- 

 lites of Mars, which measures have been taken accurately 

 nowhere else. The satellites of Jupiter and Saturn, includ- 

 ing Hyperion, the faintest of Saturn's satellites, were simi- 

 larly measured. In addition 10 measuring their brightness, 

 a large number of determinations of the positions of the 

 satellites were made. A comparison was also begun of the 

 light of the sun and stars, with the idea of reducing all 

 photometric measurements to a common standard— the light 

 of the sun. This photometric work has been continued 

 until die light of all the known satellites, except the two 

 inner satellites of Uranus, has been measured. 



One of the most important series of equatorial observa- 

 tions has been in connection with the eclipses of Jupiter's 

 satellites. These phenomena have proved exceedingly 

 valuable as a means not only of determining the orbits of 

 the satellites themselves, but of measuring the distance of 

 the sun or the velocity of light, and of obtaining terrestrial 

 longitudes. 



The observations of the mere appearance or disappear- 

 ance of a satellite, however, can not be rendered sufficiently 

 exact, and, to lessen the errors, photometric observations 

 have been made of the satellites as they gradually enter or 

 emerge from the shadow of Jupiter, using the planet itself 

 or another sate lite as a standard. 



In order to furnish means for the comparison of the 

 scales of stellar magnitude, employed by different astrono- 

 mers in their estimate of the brightness of faint stars, a 

 number of faint stars in the immediate neighborhood of the 

 north pole were selected for photometric measurement, and 

 a circular was distributed among astronomers requesting 

 estimates of magnitudes of the same stars for comparison 

 with such other, and with the results of the measurements 

 made here. A series of measurements of all the planetary 

 nebulas has also been undertaken. This work with the 

 great equatorial has necessitated the invention of a number 

 of new photometric instruments, which have been devised 

 by Professor Pickering and his assistants. 



For nearly eight years Professor Rogers has been engaged 

 upon one of the largest astronomical undertakings that has 

 been successfully completed in this country. This is the 

 observation with the meridian circle of the zone of eight 

 thousand stars, between fifty and fifty-five degrees north, 

 undertaken by this Observatory as its share in die determi- 

 nation of the position of the stars of the northern hemis- 

 phere. The observations were finished about a year ago, 

 but some years will be required to complete the reduction 

 and publication of this work. 



The total number of observations for 1879 W > ,M the meri- 

 dian circle, including about six hundred for the ('nasi 

 Survey, was nearly three thousand. The scientists at the 



Observatory are now engaged in the task of determining 

 tin: light of all the st. us visible to the naked eye in the lati- 

 tude of Cambridge, The meridian is used in observations 

 like a transit instrument in connection with a new and 

 elaborately designed photometer. 



At the .Museum of Comparative Zoology the staff of 

 Specialists is almost entirely occupied in the classic 

 and arrangement of different collections and the publication 

 of the results of their researches. The most important 



accessions during 1878 and 1879 are the extensive collec- 

 tions of the Blake dredging expedition, and the collections 

 of birds, mammals, reptiles, and fishes, made by Mr. Garman 

 at St. Kitts, Dominica. Grenada, Trinidad, St. Thomas, and 

 Porto R ; co, after he left the Blake. The Blake collections 

 and specimens from the entomological, conchological, and 

 ornithological departments are in the hands of well-known 

 specialists for final investigation. Of the extensive work 

 in progress it is impossible to give any details. The results 

 are embodied in the extensive publications of the museum. 

 Five volumes of bulletins have been published, averaging 

 about a dozen papers each. The quarto publications will 

 hereafter be issued as memoirs. The catalogues thus far 

 published have been collected into Volumes I.-1V. of the 

 memoirs. Five volumes of memoirs and the first part of 

 the sixth have already appeared. The second part of the 

 sixth and Vol. VII. are now in course of preparation or in 

 press Vol. VI. contains the great work upon which Pro- 

 fessor Whitney is now engaged, " The Auriferous Gravels 

 of the Sierra Nevada of California." The Sturgis Hooper 

 Professorship of Geology, held by Professor Whitney, is 

 noticeable as being founded solely for original research. 



The dredging operations of the Coast Survey steamer 

 Blake have not only aided zoological science by the infor- 

 mation obtained in regard to echini, corals, crinoids, ophi- 

 urians, worms, hydroids, and others, but have added to 

 geographical knowledge of the Caribbean Sea by showing 

 the changes in form and distribution of lands»along various 

 groups of islands, and in the form of the land beneath the 

 water. Professor Agassiz considers the deep-sea collections 

 of the Blake the largest and most important ever made on 

 this coast, and, when combined with the results of other 

 expeditions sent out under the auspices of the Coast Sur- 

 vey, they make the collections at the museum but little 

 inferior to those of the Challenger. During the coming 

 summer Professor Agassiz will probably undertake another 

 dredging trip in the Blake, following the course of the 

 Gulf Stream to the north of the Bahamas, and dredging 

 from the 100 to the 2,500 fathom line off the coast of the 

 United States, so as to connect the isolated district with the 

 deep-water fauna proper of the Atlantic. 



Professor N. S. Shaler, Professor of Paleontology, in ad- 

 dition to his work at the museum, and as an instructor, 

 has, since 1873, had charge of the Kentucky State Survey. 

 Four volumes of reports and one of memoirs have been 

 already completed, and one volume of memoirs and nine 

 of reports are now in press. The recent writings of Pro- 

 fessor Shaler are "The Origin and Nature of Intellectual 

 Property," and several articles in the " Proceedings of the 

 Boston Natural History Society," "The Atlantic Monthly," 

 and " The International Review." The article by Pro- 

 fessor Shaler in the latter magazine is entitled " Sleep and 

 Dreams." 



Scientific publications, based entirely or in part upon 

 the entomological collection of the museum, are the new 

 edition of the " Catalogue of the Diptera of the United 

 States," by Osten-Sacken, published by the Smithsonian 

 Institution, Part VIII. of the " Monographic Revision of 

 the European Trichoptera," by R. McLachlan, published in 

 London, and several papers by Dr. H. A. Hagen, the head 

 of the department. 



At the medical school the largest amount of original in 

 vestigation is carried on in the physiological and chemical 

 laboratories. In the former a number of new forms of ap- 

 paratus are in use, which have been designed by Professor 

 Bowditch and his assistants. Among these are an appar- 

 atus for keeping animals alive by artificial respiration ; a 

 dog-holder, canulac for observations on the vocal cords of 

 animals, without interfering with their natural respiration ; 

 unpolarizable electrodes used in studying certain problems 

 in the physiology of the nervous system ; a new form of 

 apparatus for barometric measurements ; and a novel plan 

 for measuring the volume of air inspired and expelled in 

 respiration. A new torm of plethysmograph has been 

 devised by Dr. Bowditch. This is an instrument for meas- 

 ing the changes in the size of organs, cither hollow or 

 solid, which are produced by variations in the conditions 

 to which they are subjected. The essential part of Dr. 

 liowditch's invention is a contrivance by which fluid is 

 allowed to How freely to and from the organ to be measured 

 without changing its absolute level in the receptacle into 



