6i8 



NA TURE 



[April 27, 1905 



Ephemeris I2h. {M.T. Paris). 



a 5 log : 



April 36 ... S 9 33 



27 ... 8 15 24 



28 ... 8 21 17 



29 ... 8 27 13 



30 •■■ 8 33 i> 



+ 43 I 'o 

 + 43 38 '8 

 + 44 143 

 + 44 47 J 

 + 45 17-5 



9 9247 



Bright. 

 070 



061 



Brightness at time of discovery = i-o 

 An observation by Dr. Palisa at Vienna on April 8 gave 

 a correction of +2S. and +o'-2. 



Changes on Mars. — A telegram from Mr. Lowell, pub- 

 lished in No. 4010 of the Astronomische Nachrichten, 

 announces that colour changes similar to those previously 

 reported are again taking place in some of the Martian 

 features. The Mare Erythraeum, just above Syrtis, has again 

 changed from a blue-green to a chocolate-brown colour. 

 This change was first observed by Mr. Lampland on April 4, 

 and the Martian season now corresponds to our February. 



In a communication to No. 4, vol. xiii., of Popular 

 Astronomy, Prof. \V. H. Pickering observes that ice will 

 probably begin to form at both poles of Mars during the 

 present month, the north pole being turned towards the 

 earth at an angle of io°-i3°. This opposition is particu- 

 larly favourable for observations of the green colour over 

 a greater part of the planet's surface, as Mars will be 

 more favourably situated than during the preceding or the 

 following opposition. Its apparent diameter will be from 

 13" to 17", and the poles should appear either of a pure 

 white, a light yellow, or a vivid green colour, the first 

 named being due to hoar-frost or snow, the second to 

 clouds, and the last named, in part at least, to vegetation. 



Photography of Planetary Nebul.^. — In No. 356 

 of the Observatory Mr. \V. S. Franks suggests that 

 special attention should be paid to the photography of 

 planetary nebuls by those observatories which possess 

 long-foctis cameras. Whilst using the late Dr. Roberts's 

 98-inch " Starfield " reflector, Mr. Franks attempted to 

 photograph these interesting objects both with and with- 

 out a secondary magnifier, but in the first case the images 

 obtained were indistinguishable from those of the -surround- 

 ing stars, whilst in the latter the definition was very un- 

 satisfactory. 



One point which is strongly in favour of anyone enter- 

 ing this field of research is the fact that the light emitted 

 by these objects is of a highly actinic character necessi- 

 tating only short exposures. 



Radial ^■ELOCITIES of "Standard-velocity Stars." — 

 No. 3, vol. i., of the Mitteilungen of the Nicholas Observ- 

 atory, Pulkowa, contains a number of results obtained by 

 Prof. Belopolsky for the values of the radial velocities of 

 the " standard-velocity " stars. Each of the values was 

 obtained from the measurement of about fifteen iron lines 

 on a single plate, and the date, time, and hour-angle is 

 given in each case. The stars dealt with in the present 

 publication are a Arietis, a Persei, € Pegasi, and 

 Geminorum, and taking the mean of the several values 

 given in each case the following respective velocities are 



obtained: 12-30 km., -2-14 km., -1-5-72 km. (one 



plate) and -f4 2i km. 



.Magnitl-de Eql-ation in the Right Ascensions of the 

 Eros Stars.— In Bulletin No. 72 of the Lick Observatory 

 Prof. R. H. Tucker discusses the magnitude equation 

 which enters into the observations of the right ascensions 

 of the Eros stars as observed at various stations engaged 

 in the work. Comparing the equations in the first and 

 second Eros lists, it is found that there is no marked 

 smiilarity between the two sets observed at the same 

 station ; different instruments, and probably in some cases 

 different observers, having been employed. At Lick the 

 pfTect of magnitude has been measured bv screen observ- 

 ations at three different epochs for the same obsen'er and 

 instrument. For clock stars the correction obtained was 

 o 00- second per magnitude, and, assuming it to vary with 

 decimation, this would give 0010 second and 0-008 second 

 jior magnitude for the first and second lists respectively. 

 ( onfirmation of this, in general, is found in the Konigs- 

 berg results obtained with a clock-driven micrometer in 

 which It is assumed that the magnitude equation is 

 eliminated. Other tables given show the variation of the 

 error with varying magnitudes. 



NO. 1852, VOL. 71] 



MEMOIRS ON MARINE BIOLOGY. 

 "T^HE study of marine life by the sea-side is not only a 

 delightful occupation in itself, but is now considered 

 as an almost essential part of the training of every young 

 biologist. It is also one of the most fruitful fields of 

 inquiry for the elucidation of the fundamental problems 

 of biology. Several marine stations have now been 

 erected on our coasts, in which a naturalist may gain a 

 practical knowledge of the rich fauna and flora of the 

 sea, and where he may apply those modern and often 

 expensive methods of experiment and research which cat» 

 only be carried out in a well equipped laboratory. 



Among the most successful of these institutions is that 

 of the Liverpool Marine Biology Committee, established 

 first on Puffin Island in 1S87, and subsequently moved to 

 its present quarters at Port Erin. It is chiefly due, we 

 believe, to the efforts and enthusiasm of Prof. W. H. 

 Herdman that this laboratory was founded. To help the 

 student to make good use of its resources. Prof. Herdman 

 is now editing a series of small practical monographs 

 known as the L.M.B.C. Memoirs. Much valuable 

 time may be wasted, many serious errors may be com- 

 mitted, and many precious opportunities may be lost in 

 the practical study of marine biology through the want 

 of proper guidance, or through the ignorance of the 

 literature of the subject. Well stocked libraries are rarely 

 to be found near at hand, and, moreover, it often happens 

 that the commonest animals and plants are just those 

 which have been least completely described in readily 

 accessible works. It is with a view to remedy these 

 defects that the memoirs are being published. As the 

 editor tells us in his preface, the series deals with those 

 types which have hitherto not been adequately described in 

 English text-books and laboratory manuals. 



Some thirty volumes are promised. They range over 

 almost the whole of marine life — from the diatom to the 

 sea-weed, from the sponge to the porpoise. Twelve volumes 

 have already appeared. These are : — (i) Ascidia, by the 

 editor; (2) Cardium, by J. Johnstone; (3) Echinus, by 

 H. C. Chadwick ; (4) Codium, by R. J. H. Gibson and 

 Helen Auld ; (5) Alcyonium, by S. J. Hickson ; (6) Lepeo- 

 phtheirus and Lernoea, by Andrew Scott ; (7) Lineus, by 

 R. C. Punnett; (8) Pleuronectes, by F. C. Cole and J. John- 

 stone; (9) Chondrus, by O. \'. Darbishire ; (10) Patella, 

 by J. R. A. Davis and H. J. Fleure ; (11) Arenicola, by 

 J. H. Ashworth ; (12) Gammarus, by M. Cussans. Not 

 only is a detailed and accurate account given of the struc- 

 ture of each type, but its habits, life-history, and embry- 

 ology are also dealt with, and its " economic " aspects 

 are not forgotten. 



On the whole, the various monographs seem to us 

 most trustworthy, and reflect great credit on the work of 

 the authors, who, indeed, are for the most part specialists 

 thoroughly familiar with the types they describe. Yet it 

 must be confessed that the volumes differ considerably in 

 merit and attractiveness. Some of them contain little 

 that is either new or original. Among the most interest- 

 ing of those already published we may mention the excel- 

 lent volume on the plaice, Pleuronectes, by Messrs. Cole 

 and Johnstone, which has already been reviewed in Nature, 

 also the memoir on Arenicola by Mr. Ashworth. Both 

 these seem to us models of what such monographs should 

 be — clear and practical descriptions of the anatomy and 

 life-history of the animals concerned, with some discussion 

 of the general problems suggested, and good illustrations. 

 Naturally enough the embryology is in most cases very 

 briefly described, and often the accounts provided are 

 chiefly derived from the works of other authors. We 

 question, indeed, whether it is really worth while repro- 

 ducing in such monographs figures illustrating the de- 

 velopment which can be found in almost anv text-book. 



While both a table of contrnis at the beginning, and 

 an index at the end, may not always be necessary, vet 

 it is a pity that many of the monographs should be pub- 

 lished with neither. In some cases, also, the figures are 

 scarcely clear enough ; but considering the vcrv moderate 

 price at which they are issued, the L.M.B.C. Memoirs are 

 excellently printed and illustrated. Thev will doubtless 

 fully justify the hope of the editor, and 'will prove most 

 useful to students of marine biology, who will await with 

 eagerness the appearance of the remaining volumes. 



