132 



SCIENCE. 



[Vol. II.. No. 



■periments have shown that this double reflection does 

 not occasion a great loss of liglit; and the figure and 

 polish of the silver on glass mirrors are very satisfac- 

 tory. The observatory possesses this new instrument 

 through the liberality of the well-known patron of 

 French astronomy, M. Bischoffsheira. 



In regard to physical observations, M. Egoroff, 

 professor of physics at Warsavi^, was occupied at 

 Paris during the months of July and August, as in 

 preceding years, with the spectroscopic study of at- 

 mospheric absorption, working with a beam of electric 

 light sent from Mont Valerien to the observatory. 

 In consequence of the decision of Admiral Mouchez 

 to separate special meteorological investigations from 

 the astronomical work of the observatory, meteoro- 

 logical observations of a much higher value are now 

 being made, with the special object of determining 

 the different corrections, of the nature of refraction, 

 to be applied to the astronomical observations. A 

 series of observations is to be made from a captive 

 balloon of such size, that, with ordinary gas, it can, 

 in calm weather, take self-registering barometers, 

 thermometers, and hygrometers up to a height of 

 five hundred, and with pure hydrogen to a height 

 of eight hundred metres. The balloon cannot be well 

 managed if the velocity of the wind exceeds four or 

 five metres per second; but this is not regarded as in- 

 convenient, because it is during complete calm that 

 the greatest abnormal perturbations of astronomical 

 refraction manifest themselves. Simultaneous ob- 

 servations will be made on the meridian of the Paris 

 observatory, north at the observatory of Montmartre, 

 and south at the observatory of Montsouris. 



The construction of the great refractor of 16 m. 

 focus, together with its dome 20 m. in diameter, is 

 steadily progressing. The object-glass figured by M. 

 Martin is already complete. Tlie dome is to be of 

 the same dimensions as the Pantheon, and the lar- 

 gest ever attempted. The arrangement for insuring 

 its turning with ease, and which has been adopted 

 for its construction, is that proposed by M. Eiffel. 

 In order to reduce to a minimum the friction of 

 circular rollers, he proposes to float the dome by 

 means of an annular caixson plunged in a receptacle 

 of the same form, and filled with a liquid which will 

 not freeze, such as an aqueous solution of chloride 

 of magnesium. At the Paris observatory it is quite 

 necessary that some such arrangement as this should 

 be adopted ; for the observatory is situate over the 

 catacombs, one result of which has been, that for 

 many years the pillars of the meridian-circle erected 

 in the gardens have gradually inclined toward the 

 east in consequence of the displacement of the soil. 

 With mechanism of this form for rotating the dome, 

 any pr.)bable change of level would not prevent the 

 dome from turning. 



The magnetic observatory now being completed 

 will be one of the first order. Six subterranean 

 chambers of constant temperaiture have been built 

 under the best possible conditions of isolation and 

 stability. An outer wall of nearly 2 m. thickness 

 encloses a rectangular space 40 m. in length and 

 14 m. wide, completely impervious to moisture. The 



vaulted roof, 1 m. thick, is covered by earth to the 

 thickness of 2 m., and grass and planks protect the 

 soil from the direct rays of the sun and from frost. 

 The observing chambers can be lighted either by 

 gas, or by reflection from without. 



Advantage has been taken of the existence of these 

 chambers by placing in them the clocks from which 

 the time is distributed throughout Paris; but, in spite 

 of all precautions, the chambers are found to be not 

 altogether free from minor trepidations resulting 

 from the traflBc of the streets. Apparatus lias been 

 constructed, and is now ready for use in investigat- 

 ing the vertical and slow movements of the soil. This 

 will be placed in a gallery in the catacombs 27 m. 

 below the surface. 



The erection of an astronomical observatory on 

 the Pic du Midi, at a height of 2,8-59 m., is engaging 

 the attention of the director. At this elevation, it is 

 said to be easy to read at night by starlight alone, 

 and fifteen stars are visible to the naked eye in tlie 

 cluster of the Pleiades. It is intended that any as- 

 tronomer who wishes to make any special researches 

 may take advantage of the observatory on the Pic 

 du Midi. 



LETTERS TO THE EDITOR. 



The right whale of the North Atlantic. 



I HAVE noticed in a late number of your journal 

 a criticism on the last Bulletin of the American 

 museum of natural histoi'y. Being away from town, 

 I have not access to works referring to the subject 

 of cetology; but with the aid of notes that I have 

 with me, as well as drawings of the subjects involved, 

 I hope to show conclusively that other views than 

 those taken by the critic are the correct ones. 



I shall not attempt to justify the carelessness that 

 permits the presence of typographical errors; but, 

 when an errata list accompanies a work, it should 

 have due credit for its intentions. 



The writer says, "There are errors of statement 

 of so grave a character as to require notice," and 

 continues, "It would seem, for instance, that only 

 the merest novice in cetology could have been mis- 

 led," etc. — referring to the identity of the St. Law- 

 rence whales. 



Lesson wrote, "What an impenetrable veil covers 

 our knowledge of the Cetacea! Groping in the dark, 

 we advance in a field strewn with thorns." I believe 

 that some in later days, not quite novices, admit a 

 degree of unfamiliarily with the great beasts of the 

 sea. In that view, let us see if ' errors of statement 

 . of grave character ' have really been made. 



The president of the Quebec historical society. Dr. 

 Anderson, with Dr. DeKay's Report on mammalia 

 before him, says, speaking of a large whale that had 

 foundered in the St. Lawrence River, "It turned out 

 to be an aged male, apparently the species Balaena 

 mysticetus. . . . The back was black ; the belly, fur- 

 rowed, presenting the appearance of a clinker-built 

 boat. ... I concluded, after a careful examination, 

 it answered fully the description given by Dr. DeKay 

 for the mysticetus. ... As the whale lay upon the 

 beach, he was sixty-five feet long; the fluke of his 

 tail was twelve feet; his jaw, fifteen feet." 



This whale was noticed primarily by us for the pur- 

 pose of directing attention to the fact, that such a 

 great form liad really pushed into the fresh-water 



