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POPULAR SCIENCE MONTHLY. 



tire success under all kinds of condi- 

 tions. The inventors are Mr. Walter 

 Jameson and Mr. John Trotter. It is 

 stated that Nikola Tesla has American 

 patents for a somewhat similar device. 



In the absence of the author, Pro- 

 fessor Dewar's paper on the solidifica- 

 tion of hydrogen Avas read in the Brit- 

 ish Association by Sir William Crook. 

 It shows that solid hydrogen presents 

 the appearance of frozen water, and not, 

 as had been anticipated by many, of 

 frozen mercury; hence it is now defi- 

 nitely decided that it is not metallic. 

 The temperature of the solid is 16° ab- 

 solute at thirty-five millimetres pres- 

 sure, and it melts at 16° or 17° abso- 

 lute, the practical limit of the tempera- 

 ture obtainable by its evaporation being 

 14° or 15° absolute. Thvis the last of 

 the old gas has been solidified. It 

 was further mentioned, in connection 

 Avith these statements, that Professor 

 Dewar had succeeded in liquefying he- 

 lium. 



The organizing committees of the 

 Congresses of Aeronautics and Meteor- 

 ology — these being cognate subjects — of 

 the Exposition of 1900 have decided to 

 hold the meetings of these bodies in 

 such a manner that all members can 

 attend the sessions of both. The pro- 

 gramme arranged for the Aeronautical 

 Congress contemplates the discussion, 

 under aspects which are set forth in de- 

 tail, of "problems" relating to free bal- 

 loons, their management and use; cap- 

 tive balloons, steerable balloons, and 

 aviation; and the scientific applications 

 of balloon observations to problems in 

 astronomy, meteorology, and physiol- 

 ogy; also of their use for purposes of 

 reconnoissance and topographical sur- 

 veys, and of photography from balloons. 

 In a difTercnt order of ideas, the con- 

 gress may occupy itself with questions 

 of legislation and international law 

 which concern aeronauts in times of 

 peace and of Avar. 



Three State catalogues of Ohio 

 plants have heretofore been issued. The 

 first, by J. S. Xcwbcrry, Avas published 

 in the State Agricultural Report in 

 18.5!); the second, by H. C. Beardslee, 

 Avas published in 1874, and Avas rc- 

 ]>vinted in the Agricultural Report for 

 1870; and the third, by W. A. Keller- 

 man and ^\^ C. Werner, AA'as included 



in the State Geological Report for 1893. 

 This Avork contains a bibliography, and 

 giACS the names of the first known col- 

 lectors of the less common species. A 

 fourth catalogue, consisting of a check- 

 list of the Pteridopltytcs and Spcrmo- 

 pJiytes, recently published by Prof. W. 

 A. Kellerman, contains the species and 

 A'arieties numbered serially, as in the 

 State Herbarium of nearly ten thousand 

 sheets, Avith the sequence of groups as 

 by Engler and Prantl, and the nomen- 

 clature as used by Britton and BroAvu. 



NOTES. 



The committee of the St. Peters- 

 burg Astronomical Society for the revi- 

 sion of the Russian calendar, to make 

 it agree Avith the Gregorian, has found 

 it necessary to move sloAvly. The festi- 

 vals prove a formidable obstacle to the 

 desired reform, and the people Avill have 

 to be prepared for the change before it 

 can be instituted. The plan noAV is to 

 use both dates, Russian and Grej^ "n, 

 together till the ncAV style can be muJe 

 familiar, and it is proposed to make the 

 double use compulsory on private as 

 well as on public documents and papers. 



A steamboat company is placing 

 its little A^essels on the canals of Venice, 

 and the gondolas, Avhich Avere one of the 

 charms of the city to travelers, are des- 

 tined to disappear — unless a fcAV may 

 be reserved to gratify the curiosity of 

 tourists. 



The Commissioner of Education of 

 Rhode Island has issued a circular to 

 teachers, calling attention to the work 

 of the Audubon Society for the Preser- 

 A'ation of Birds, and to the incalculable 

 value, from \'arious points of A'ieAV, of 

 bird life, and advises them to foster 

 Nature study as furnishing a natural 

 channel by means of Avhich instruction 

 and information on the subject may 

 readily be brought before the children, 

 and through them to the people gen- 

 erally. 



Is a paper on The Ultimate Basis 

 of Time Divisions in Geology, T. C. 

 Chamberlin accepts it as proved that 

 there Avere no universal breaks in sedi- 

 mentation or in the fundamental con- 

 tinuity of life, no physical cataclysms 

 attended by uniA'crsal destruction of 

 life, and that sedimentation has been in 

 constant progress somcAvhere and life 



