552 



NATURE 



\Oct. 6, 1887 



necting-rod was disconnected, and the piston was rigidly blocked 

 at the end of the stroke furthest from the crank, the interior of 

 the cylinder surrounding the piston-rod being entirely filled up 

 with wood and iron packing. The steam passage between the 

 valve seat and the end of the cylinder next the crank was also 

 solidly filled up ; and the port itself was closed by a brass plate 

 scraped down to the level of the valve seat. The port admi:ting 

 steam to the end of the cylinder furthest from the crank was left 

 open ; and the crank shaft, eccentric, and valve were driven by 

 another engine. The steam pressure in the boiler was main- 

 tained at a uniform amount, and the regulator was kept open 

 during a trial. The steam was measured by connecting the 

 exhaust port with a surface condenser and collecting the result- 

 ing water. The results of the experiments appeared to indicate 

 that the net initial condensation, or excess of condensation, over 

 re-evaporation by the clearance surface varies directly as the 

 initial density, and inversely as the square ro it of the number of 

 revolutions per unit of time. The paper was discussed, and 

 was followed by one on irrigating machinery on the Pacific 

 coast, by Mr. John Richards, which dealt very fully with the 

 forms of pumps required for the various services to be performed. 

 The discussion of this paper was adjourned. 



Paris. 

 Academy of Sciences, September 26. — ^^M. Herve Mangon 

 in the chair. — On the recent waterspout in Lake Geneva, by M. 

 H. Faye. In reply to M. Ch. Dufour's letter stating that several 

 persons had noticed an ascending gyratory movement in the 

 waterspout that swept over Lake Geneva on August 19, the 

 author points out that, although the movement is really descend- 

 ing, as he holds against most meteorologists, there is nothing re- 

 markable in this apparent contradiction, which is due to a purely 

 optical illusion on the part of the observers. In the same 

 way the spirals of a vice or screw, placed vertically to a hori- 

 zontal base, when turned in the reverse direction, seem to 

 the spectator to ascend along the line of the main axis, pre- 

 senting the appearance of continually retiring from the base 

 upwards, and buryin'^ itself in the handle or top cross-piece. 

 The cause of the illusion is simple enough. Each anterior 

 semi-spiral is Successively replaced, as the screw revolves, by 

 the posterior half, which, being at a higher level, the visible 

 half-spirals, taken separately and together, seem to ascend. 

 So with waterspouts, which, as already repeatedly explained, 

 never ascend, but always descend, being the result of forces 

 having their existence in the upper atmospheric regions. — On 

 the measurement of the forces brought into play in the flight 

 of a bird, by M. Marey. Anatomy shows that nearly all the 

 muscles acting on the wing serve to lower it, while the kine- 

 matic data drawn from photo-chronography show that during 

 this lowering of the wing the mass of the bird is upheld against 

 gravity and propelled forward against the resistance of the air, 

 the result being flight. The author here studies these two ele- 

 ments of the motor power separately, whence may ultimately be 

 deduced the sum total of the motor power. — Remarks accom- 

 panying the presentation of vol. xiii. of the " Memorial du Depot 

 de la Guerre, " by General Perrier. This volume is occupied exclu- 

 sively with the operations connected with the extension of the geo- 

 detic and astronomic lines from Spain to Algeria. — Observations 

 of Brooks's comet (August 24), made at the Observatory of Algiers 

 with the o'50m. telescope, by MM. Trepied, Rambaud, and Sy. 

 The observations extend over the period from September lo to 

 16, and give the positions of six comparison stars of the eighth 

 and ninth magnitudes. — Observations of the same comet at the 

 Observatory of Lyons with the O'iSm. Brunner equatorial, by 

 M. Le Cadet. The observations cover the period from Septem- 

 ber 13 to September 21. — Positions of Barnard's comet (O^May 

 12, 1887) and of Palisa's new asteroid (September 21, 1887), 

 measured at the Observatory of Besan9on, by M. Gruey. The 

 observations of the comet run from June 13 to July 23. TJiose 

 of the asteroid were taken with the 8-inch equatorial on Septem- 

 ber 23. — On the relative distances of the planets in relation to 

 the sun, and on the distances of the periodical comets, by M. 

 Delauney. The planetary distances being represented by the 



formula D = 86' °^ , where n receives the successive values 

 I, 2, 3, 4, . . . . , the unity of distance is the semi-diameter of 

 the sun, and if this unity be changed and the distance be taken, 

 for instance, of the earth from the sun, the formula becomes 



D = 0-0032680 X 86''°^^^ . The calculation shows that with 

 this same unity the mean distances of the six known periodical 



conxets from the centre of the sun may be one presented by the 



n 

 analogous formula D= I '8940 X i"i5ii^ . Further considera- 

 tions show that there exists a gap in the series corresponding to 

 « = 1, and that seven comets may be regarded as forming a 

 single group analogous to the minor planets of the solar system. 

 The distances increase so rapidly with n that for « = 6 

 we get 15,455, corresponding to a periodicity of nearly 

 2,000,000 years. Other considerations lead to the infer- 

 ence that the periodical comets appear to be produced by 

 the cosmic matter of the zodiacal light. — Researches on 

 the spheroidal state, by M. E. Gossart. The author here 

 seeks to determine by calculation and experiment the meridional 

 semi-section of any liquid drop whatsoever in a state of calefac- 

 tion on a horizontal plaque. It is shown that there exists a 

 characteristic form of the spheroidal state, which may easily be 

 represented graphically according to a given scale. The measure- 

 ments of the various elements of these curves may furnish useful 

 information on the capillary constant. — On the distillation of 

 citric acid with glycerine, MM. Ph. de Clermont and P. 

 Chautard. The product of the process here described presents 

 absolutely the same properties as the pyruvine obtained by 

 distilling a mixture of tartaric acid with glycerine, although it 

 seems difficult to explain how the same substance should result 

 from the distillation, in the presence of glycerine, of an acid 

 such as citric acid, which differs so greatly from tartaric acid. — 

 On the development and structure of young Orobanches, by M. 

 Maurice Hovelacque. Since M. Caspary's observations on the 

 germination of the Orobanches {O. cruenta, O. raviosa, O. minor, 

 O. Hcdera:), dating from 1854, nothing was published on the 

 subject till its study was resumed by Koch in 1883, the results 

 being published in a comprehensive memoir recently issued by 

 him. In the present communication M. Hovelacque indicates 

 several important points where his own observations difl'er con- 

 siderably from the conclusions of the learned German botanist. 



BOOKS, PAMPHLETS, and SERIALS RECEIVED. 



Exercises in Quantitative Chemical Analysis, including Gas Analysis : 

 W. Dittmar (Hodge). — Weather Charts and Storm Warnings, 3rd edition : 

 R. H. Scott (Longmans). — Proceedings and Transactions of the Royal 

 Society of Canada for i885, vol. iv. (Dawson, Montreal). — Report of the 

 Voyage of H. M.S. Challenger, vol. xxi. 2 Parts, Zoology. — An Elementary 

 Treatise on Kinematics and Dynamics: J. G. Macgregor (Macraillan). — 

 Key to Todhunter's Conic Sections : Edited by C. W. Bourne (Macmillan). 

 — Handbuch der Palaeontologie, r. Abth. Palaeozoologie, 3 Band, i Liefg. 

 (Williams and Norgate). 



CONTENTS. PAGE 



Alphita. By Dr. J. F. Payne 529 



Our Book Shelf :— 



" Fresh Woods and Pastures New " 530 



Letters to the Editor : — 



The British Museum and American Museums. — 



Dr. Alfred R. Wallace 530 



The Law of Error,— T. W. Backhouse 531 



Lunar Rainbows.— A. F. Griffith ; S. J. H. ... 531 



The Perception of Colour. — T. W. Backhouse . . 531 

 Tertiary Outliers on the North Downs. — Rev. A. 



Irving 531 



Modern Views of Electricity. Part I. — I. By Dr. 



Oliver J. Lodge, F.R.S. {Illustrated) 532 



On the Teaching of Chemistry. By M. M. Pattison 



Muir 536 



Botany of the Riukiu (Loochoo) Islands. By 



Tokutaro Ito 53a 



Notes 539 



Our Astronomical Column : — 



Flamsteed's Stars " Observed but not Existing " . . 54^ 



Corrigenda in various Star-Catalogues 543 



The "Satellite" of Venus 543 



The Leander McCormick Observatory 543 



The Nice Observatory 5431 



Astronomical Phenomena for the Week 1887 



October g-15 54 



Geographical Notes 54 



Meteorological Notes 5451 



The British Association : — 



Section A. — Mathematical and Physical Science . . 54^ 



Scientific Serials 55' 



Societies and Academies 55'. 



Books, Pamphlets, and Serials Received 



