548 



NATURE 



[April 4. 1901 



noticed in these column?. The observations secured during the 

 year will, when worked up, affjrd an accurate knowledge of the 

 times of the tides and of the turning of the tidal streams in the 

 lower St. Lawrence. Many new observations of the tide-levels 

 at different stations have also been obtained. 



A METHOD for the preparation of amides from the correspond- 

 ing aldehydes, which appears to be of general application, is 

 described by Messrs. Pickard and Cirter in the April number of 

 the Journal of the Chemical Society. The aldehyde dissolved 

 or suspended in water is shaken with a slight excess of ammo- 

 nium persulphate and a certain quantity of lime, and after the 

 reaction is over there is no difficulty in separating the amide in 

 quantities amounting to 30 to 40 per cent, of the aldehyde 

 taken. The method also lends itself to the preparation of alkyl- 

 substituted amides, potassium persulphate being substituted for 

 the ammonium salt and the alkylamine being present. 



The following species, among others, have been taken at 

 Plymouth recently by the Marine Biological Association : — Mol- 

 lusca : yEolis aurantiaca, Gastrochaena modiolina. Crustacea : 

 Achaeus Cranchii. Polychseta : Magelona papillicornis, 

 Oivenia fusifortjiis, Scaliselosus assiinile. Echinoderma : 

 Ophioaiida brachiata. Hydrozoa : Heterocordyle Conybeari, 

 Syncoryne Loveni. The pelagic fauna is increasing in rich- 

 ness and variety. The following have been taken : — Medusae : 

 Amphicodon amphipleurus, Margeliuin octopunctatum. Crus- 

 tacese : Podon inlennedius ; large numbers of the nauplii and 

 the Cypris stage oi Balanus. Polychseta : post-larval stages of 

 Arenicola, Trochospheres and later larvse of Polynoids and 

 Phyllodocids. Among the species breeding may be mentioned 

 the following : — Crustacea : Porcellana platycheles, Zanlho 

 rivulosus ; several species of Portunus and Stenorhynchus 

 pkalangittni. Polychseta : Myrianidx pennigera, Polynoe scolo- 

 pendrina. Hydrozoa : Hydrallmania falcata, Tubular ia 

 'indivisa, Syncoryne Loveni, Garveia nutans, Diphasia rosacea, 

 Sertularia argentea, Eudendrium ramosuin. 



The additions to the Zoological Society's Gardens during 

 the past week include a Vulpine Phalanger {Trichosurus vulpe- 

 cula) from Australia, presented by Mr. R, Kirkwood ; a Patas 

 Monkey {Cercopithecus patas) from West Africa, presented by 

 Mr. H. E. Jung ; a Common Coot ( FuHca atra), European, 

 presented by Mr. M. C. H. Hammond ; two Picui Doves 

 {ColuDibula picui) from South America, a Red-vented Bulbul 

 {Pycnonotus haemorrhous) from India, presented by Mr. D. 

 Selh-Smith ; a Huanaco {Lama huanacos) from Bolivia, a 

 Tawny Eagle {Aquila naevioides) from the Seychelles, a Nilotic 

 Crocodile {Crocodilus niloticus) from Africa, four Menobranchs 

 {Necturus maculatus) from North America, a West African 

 Python {Python sebae) from West Africa, deposited ; two Straw- 

 necked Ibises {Carphibis spinicollis) from Australia, purchased ; 

 a Sykes Oriole {Oriolus kundoo), received in exchange. 



OUR ASTRONOMICAL COLUMN, 



RUTHERKURD MEASURES OF PLEIADES. — In the Contribu- 

 tions from the Observatory of Columbia University, No. 17, 

 Mr. Harold Jacoby furnishes a revised discussion of the series 

 of measures made by Rutherfurd of photographs of the Pleiades 

 group dating from the years 1872 and 1874. The results of the 

 first investigation were published in 1892, and are slightly modi- 

 fied in the present paper. Special reductions have been made 

 to 'test the possibility of there being systematic errors arising 

 from some form of optical distortion of the object-glass, and 

 comparisons are given of heliometer and photographic measures. 

 The final data are collected to form a catalogue of seventy-five 

 stars in the cluster. 



Catalogue of Southern Variable Stars. — Mr. Alex- 

 ander W. Roberts has recently published in the Astronomical 

 /ournal {^os. 491 492) a catalogue of the positions, magnitudes 



NO. 1640, VOL. 63] 



and elements of variable stars south of - 30° declination, reduced 

 from observations made at the Lovedale Observatory with a 

 3^-inch telescope during the years 1891-1899. In connection 

 with the elements a new departure has been made by considering 

 the epoch of a variable as the first maximum passage during 

 1900, all the stars being uniformly treated on this plan, except 

 that Algol-variables are reckoned from the first minimum 

 passage. 



The author finds that the short-period variables have a mean 

 variation of i magnitude, while the variation of .the long-period 

 class amounts to about 4*0 magnitudes. Reference is made to 

 the possible connection of distinctive colours to the various types 

 of variables. 



The catalogue gives particulars of ninety-three variables, 

 copious notes being included in explanation of individual stars. 



ON A SOLAR CALORIMETER DEPENDING 



ON THE RA TE OF GENERA TION OF 



STEAM. 



"T^HIS instrument was shortly described in a note^ which was 

 ■*• communicated to the Royal Society of Edinburgh in July, 

 1882, and it has been fuUy'described and figured in a paper^ read 

 before the Philosophical Society of Cambridge in December, 1900. 

 In this paper the results obtained in Egypt in 1882 are detailed 

 and discussed. 



My object in designing the instrument and in taking it to 

 Egypt was to find out for myself the amount of heat which can 

 be actually collected from the sun's rays at or near the sea- 

 level under favourable conditions. In such circumstances this 

 amount must fall on land and sea alike, and it is the energy of this 

 radiation which maintains the terrestrial economy. 



The instrument measures the sun's heat in the same way as 

 the calorific value of other fuels is commonly measured, namely, 

 by the quantity of boiling water which a given quantity of it can 

 transform into steam of the same temperature in a given time. 

 The quantity of the sun's radiation used is measured by the 

 capacity of the reflector which collects it. The reflector concen- 

 trates it on the boiler, which is a silver tube with blackened sur- 

 face, placed in the focus of the reflector. Some radiation is 

 necessarily lost at the reflector and some at the surface of the 

 boiler, because perfect reflectors and perfect absorbers do not 

 exist ; but, when the distillation has been started and is in full 

 running, the whole of the heat which penetrates the boiler is 

 used in transforming water into steam, which is retransformed 

 into water in the condenser and measured in the receiver. A 

 portion of the heat of condensation is utilised in raising the feed 

 water to the boiling temperature before entering the boiler. 



The details of construction and the dimensions are fully set 

 forth in the paper printed in the Proceedings of the Cambridge 

 Philosophical Society. It will be sufficient here to give a brief 

 summary. Fig. i shows a general view of the calorimeter 

 mounted equatorially on a tripod. Fig. 2 shows the calorimeter 

 in section. The sun's rays are collected by the reflector 

 Bj Bj B3 B4, which consists of three conical mirrors, Bj b,, Bj B3 

 and B3 B4, so constructed that rays of light, parallel to the axis 

 of the instrument o p, falling upon these mirrors are all reflected 

 upon the length a B of the axis, a B is the focal line of the 

 reflector. The mirrors are carried by arms, as shown, which 

 are attached to the central tube c K. This tube, which is 

 twelve inches long and has a diameter of two inches, is the 

 condenser. It is connected by an india-rubber tube with the 

 glass funnel z, through which it is filled and by means of which 

 the height of the water in the upper and narrower tube c A can 

 be regulated.. The portion a B of this tube is the boiler. It is 

 of silver, blackened outside, and has a circumference of 37 

 millimetres. When the instrument is pointed to the .sun all the 

 rays which strike the mirrors are reflected upon this surface, 

 which has an area of i8*8 square centimetres. The effective 

 collecting area of the reflector is 904 square centimetres, so that 

 the rays are concentrated 48 fold. The glass funnel z is set so 

 that the level of the water inside the calorimeter stands some- 

 where between E and F. F G H is a glass tube or dome which 

 performs the functions of a water-gauge, a steam space and a 

 means of watching the distilling operation with a view to being 

 perfectly assured that there is no priming. The tube g L in the 



1 Proceedings of the Royal Society of Edinburgh, 1882, xi. 827. 



2 On a solar calorimeter used in Egypt at the total solar eclipse in 1882. 

 By J. Y. Buchanan, F.R.S. Proceedings oi the Cambridge Philosophical 

 Society (igoo), xi. pp. 37, 74. 



