282 



NATURE 



[December 29, 1910 



■the glass stem and wire supports of the filament. It is 

 obvious that the use of copper, even in small quantities, in 

 the leading-in wires of these lamps must be avoided. 



The device of doubling a wire on itself before winding 

 it into a resistance coil reduces the inductance of the coil 

 to a very small quantity, but unfortunately introduces a 

 •considerable capacity, which is equally undesirable if the 

 •coil is to be used in alternating-current measurements. 

 ■Chaperon's method of winding the coil in sections, in 

 each of which successive layers are wound in opposite 

 •directions and the magnetic area of each layer made the 

 same, reduces the capacity considerably, but the more 

 recent suggestion to balance residual inductance and 

 ■capacity has been taken up by Dr. E. Orlich, of the 

 Reichsanstalt, with marked success. He winds one layer 

 of wire on a slate slab 5 by 12 centimetres and 3 or 4 

 millimetres thick with rounded edges, then places bridges 

 over the edges and winds the second layer over the bridges. 

 The distance between the two layers of wire is calculated 

 so as to make the capacity and inductance equal for fre- 

 quencies not very high. The results of the calculations are 

 tabulated for resistance coils exceeding 3000 ohms, below 

 which the method is not applicable. 



We have received from Messrs. J. J. Griffin and Sons, 

 Ltd., a new edition of " Scientific Handicraft." The 

 volume, which contains more than one thousand pages, 

 forms a very comprehensive catalogue of physical 

 apparatus. Messrs. Griffin, in addition to supplying all 

 that is most recent for advanced work in the phj^sical 

 laboratory, include in their list apparatus which is suit- 

 able for many technical industries. The catalogue is also 

 Issued separately in three parts, the first part dealing with 

 laboratory fittings and apparatus for general physics, the 

 second part with heat, light, and sound, and the third 

 part with electricity and magnetism. The book is well 

 illustrated, and is furnished at the end with tables of 

 physical constants. It will no doubt find a place in all 

 physical laboratories as a book of reference. 



In a paper on the winning of coastal lands in Holland, 

 read by Mr. A. E. Carey before the Institution of Civil 

 Engineers on December 20, some interesting facts were 

 given with reference to the gradual reclamation of the 

 Dutch lowlands from the sea. The principal reclamations, 

 which have so largely altered the map of Holland, were 

 described, particularly that of the Lake of Haarlem, the 

 first reclamation of which was carried out between the 

 years 1540 and 1648. The so-called lake consisted of a 

 vast swamp. The final works of reclamation were 

 carried out by the State in 1840. Several of the breaches 

 in the sand dunes on the North Sea coast appear to repre- 

 sent former embouchures of the River Rhine. The level 

 of Amsterdam Peil, worked to by the Dutch engineers, 

 differs only by about i foot from the level of the Ordnance 

 datum. Some interesting facts ascertained in connection 

 with the borings for the water supply of the City of 

 Amsterdam were cited to show the delicate balance in 

 water pressure which exists in the substrata of the Dutch 

 fenlands. The gradual weakening of the natural protec- 

 tion afforded by the sand dunes was referred to, and some 

 interesting evidence was brought forward to show how 

 great the alterations in the position and magnitude of the 

 dunes have been. Changes in location of the sand dunes 

 are arrested by the planting of grasses on the faces of the 

 dunes, and the protection of them on the land side by 

 the planting of various kinds of trees. The controversy 

 proceeding in Holland as to the best procedure in carrying 



NO. 2148, VOL. 85] 



out the project for the reclamation of the Zuyder-Zee, 

 which involves the reclamation of 1,500,000 acres, was 

 mentioned. Briefly, the alternative schemes are : — (i) to 

 close the inland sea by a reclamation dam running from 

 Wieringen to the coast of Friesland, near Piaam, thus 

 shutting out the North Sea from the area to the south, 

 the reclamation works being effected at leisure in the lake 

 which would then be formed behind the dam ; (2) to carry 

 out the series of smaller reclamations before the closing 

 of the entire sea. 



The report of the Clifton College Scientific Society for 

 the year 1909-10 has been received. We are glad to find 

 that useful practical work continues to be done in the 

 various sections into which the society is divided. An 

 interesting series of notes on the birds of the Clifton 

 neighbourhood, arranged chronologically, is published with 

 the report. 



OVR ASTRONOMICAL COLUMN. 



The Spectrum of the America Nebula. — In a paper 

 published in the Sitzungsberichte der Heidelberger 

 Akadetnie der Wissenschaften (1910, No. 27) Dr. Max 

 Wolf discusses spectrograms of the America nebula taken 

 during October. The spectra were photographed with the 

 Zeiss spectrograph, having two U.-V. prisms, attached to 

 the Heidelberg reflector. 



Referring the emission lines of the nebula spectrum to 

 several Fraunhofer lines occurring in the stellar spectra 

 shown on the same plate. Dr. Wolf finds for the former , 

 the following wave-lengths :^434, 412, 406, 389, 383, 373,] 

 and 343. Of these the chief lines occur at 410-2 (412),! 

 383-7, 372-7, and 344-8 /Mfx, the line at \ 373 being by far 

 the brightest. 



The Movements of Certain Stars, in Space, Compared] 

 WITH THAT OF THE SuN. — As an cxtract from the November] 

 Bulletin Astronomique we have received a paper in whichl 

 Dr. P. Stroobant shows that the sun is probably a unit] 

 in a stream of stars moving through space in the samel 

 direction with a common velocity. As a primary index he] 

 takes those stars of which the movements, relative to the] 

 sun, are small, and then reduces their movements to a] 

 common plane. 



The result is certainly striking, for Dr. Stroobant shows! 

 that the seven stars a Cassiopeiae, )3 Persei, o Persei,! 

 o Scorpionis, 7 Cygni, e Pegasi, and o Pegasi are alJl 

 travelling towards a jxilar area of only 14° radius, with! 

 velocities ranging between 11 and 22 km. ; towards thei 

 centre of this area the sun is moving at a rate of 19-4 km. 

 The probability that of the 105 stars brighter than magni- 

 tude 2-5 seven should, accidentally, shows this common 

 motion, is very small, but it must be borne in mind that 

 the data on which the result is based are, especially in 

 the case of parallax, open to corrections. 



Dr. Stroobant suggests that, with the accumulation of 

 further, more trustworthy, data, other stars may be found 

 to belong to the same stream, and he cites y Pegasi, 

 7 Persei, C Geminorum, o Hydrae," € Leonis, »j Leonis. 

 ^ Ursas Majoris, t] Virginis, 7 Aquilae, o Pavonis, and 

 jj Pegasi as stars having small proper motions, and of 

 which the radial velocities relative to the sun are also 

 small. 



The Italian Observatories. — In the Rivista di Astro- 

 nomia (Turin) a series of articles is appearing describing 

 in detail the various Italian observatories. In No. 10 

 Signor C. H. Loviselmi gives an excellent description of 

 the observatory of the Roman College. The account gives 

 the history of the observatory, describes the buildings and 

 instruments, and gives short accounts of the various 

 observers ; it is illustrated with photographs of the build- 

 ings and portraits of Vico, Secchi, Ferrari, and Tacchini. 



Astronomy at the Brussels Exhibition. — An interest- 

 ing account of the astronomical exhibits at the Brussels 

 Exhibition is given by Dr. Stroobant in the Bulletin de 

 la SocUtd astronomique de France, and now published as 



