664 



SCIENCE. 



[N. S. Vol. XXI. No. 539. 



probable, as suggested, that petroleum was 

 formed from the oil found in. the protoplasm 

 of diatoms. This was answered in the nega- 

 tive by Dr. Mann. Dr. E. L. Greene asked 

 if any of the biologists present knew of a 

 Eatinesque other than the one who has con- 

 tributed so fully to American science. No 

 one replied, and Dr. Greene then stated that 

 in a list of botanical authors, printed at 

 Zurich, Switzerland, in the year 1772, occurs 

 the name of P. I. Rafinesque. He is credited 

 with the authorship of an essay on economic 

 botany, purporting to have been published in 

 ' Memoirs of the Society for Economics,' at 

 Berne, the date of the volume being 1763. 



The first regular paper of the evening was 

 by Dr. E. L. Greene, on the ' Earliest Local 

 Flora.' The speaker gave a sketch of the 

 ' Flora Hercynia, a Catalog of the Plants of 

 the Harz Mountains,' by Dr. Joahnes Thalius, 

 published at Nordhausen, Germany, in 1588 ; 

 a work in which many new plants are named 

 and defined, besides several genera; among 

 these Ahinanthemum, a type known since 

 Linmeus by the name of Trientalis; also even 

 that more than two centuries later indicated 

 as if new under the name Eleocharis R. Br. 



The second paper on the program was by 

 Mr. David White, on ' Fossil Plants of* the 

 Group Cycadofilices.' This paper was pro- 

 fusely illustrated with lantern slides. Mr. 

 White gave a synopsis of the* Pteridospenneae, 

 describing the more important and interesting 

 anatomical characters of the stems and 

 petioles, and illustrating a number of foliar 

 types and fruits more or less definitely corre- 

 lated with the other parts of the plants. A 

 number of genera, including Eremopteris, 

 Triphyllopteris, pseudopecopteris and Megal- 

 opteris, were tentatively referred to the 

 pteridosperms, which are to be regarded as 

 comprising the most characteristic plant life 

 of the Carboniferous. Attention was called 

 to the antiquity (Middle Devonian) of one of 

 the types, Kalymma grandis, and the conse- 

 quent probable antiquity of the heterosporous 

 Filiees which must have antedated the Cycado- 

 filices. 



E. L. Morris, 

 Recording Secretary. 



THE NEW YORK ACADEMY OF SCIENCES. SECTION 

 OP ASTRONOMY, PHYSICS AND CHEMISTRY. 



The regular meeting of the section was held 

 at the American Museum of Natural History 

 on Monday evening, March 20. The program 

 consisted of the following papers: 



The Sixth Satellite of Jupiter: S. A. Mitch- 

 ell. 



Dr. Mitchell gave an interesting account of 

 the recent discovery of a sixth, and also a 

 seventh, satellite of Jupiter by Professor C. 

 D. Perrine at the Lick Observatory, and de- 

 scribed the details of the photographic method 

 by which these satellites were discovered last 

 December and January. 



Dr. Mitchell also spoke of the discoveries of 

 satellites of the other planets, including the 

 ninth satellite of Saturn which was found by 

 Professor W. H. Pickering in August, 1899. 



A Pocket Form of the New Piezic Barometer : 



Ernest R. von Nardroff. 



The Piezic barometer measures the atmos- 

 pheric pressure by measuring the elasticity of 

 a portion of air. In the small pocket form of 

 the instrument exhibited, a piece of heavy 

 barometer tubing of 3 mm. bore and about 

 12 cm. long was provided at its lower end 

 with a pear-shaped bulb, having an internal 

 volume equivalent to about 70 cm. length of 

 the tube. At its upper end the tube was pro- 

 vided with a second small bulb containing 

 about 1 c.c. of mercury. Entering into the 

 tube from above was a short tube having at 

 its lower end a capillary opening. " Through 

 this tube the mercury was introduced. 



In using the instrument all the mercury is 

 brought into the upper bulb by inverting. 

 The instrument is then turned into the erect 

 position, when the mercury enters the main 

 tube a few centimeters, the exact distance 

 depending upon the atmospheric pressure. 

 The less the pressure and hence the less the 

 elasticity of the air, the more the mercury 

 will enter. The mercury stands in the upper 

 portion of the tube and partly in the upper 

 bulb without any tendency to run down the 

 sides of the tube. A scale on the main tube 

 drawn hy comparison with a standard barom- 

 eter indicates the pressure. 



