In.v 



1910] 



NATURE 



actual practice as observed in monuments. As at Avebury 

 and Stonehenge, the avenue was added to the circle. Each 

 stone selected has a fairly straight side, which has been 

 utilised as an independent alignment. The avenue, as well 

 as the tallest stone, are approximately oriented to the 

 sun's place on St. David's Day, March i. Three divisions 

 of the year, and alignments to sunrise or sunset for every 

 three weeks, are provided by the stones. The use of each 

 stone will be found by keeping its straight side to the 

 right. The diameter of the circle is 27 feet ; the length of 

 the avenue 54 feet; the total length of the work is 81 feet. 

 In all such measurements, the Gorsedd rule that all 

 extensions should be in threes, or multiples of three, was 

 observed. The width of the avenue represents the 

 distance, as measured on the horizon and viewed from the 

 centre stone, between Candlemas and the equino.x. True 

 to ancient practice, the westward view of the avenue is 

 " blocked " by a stone, which otherwise represents the 

 fashion in Aberdeenshire circles, noticed by Sir Norman 

 Lockyer, of placing a stone at right angles to the direc- 

 tion required. John Griffith. 

 Llangynwyd, Glam. 



Halley's Comet. 



I DO not know if the enclosed is of any general interest 



or not ; it is an attempt to photograph Halley's comet (as 



seen here) without any special apparatus. The tail was 



about 90° long on May 17, and probably 115° on May 18, 



Halle) 



taking the calculated position of the nucleus, which had 

 not risen when dawn came. On May 20 (on the other 

 side) the tail was only 15° or 20° long, but both twilight 

 and moon interfered. It was 35° long on May 23. 



James Moir. 

 .Mines Department, Johannesburg, June 10. 



Earth. current Obseivations in Stockholm duiing the 

 Transit of Htlley's Comet on May 19. 



When Halley's comet was passing across the sun on 

 May 19 we took, at the central telegraph station at Stock- 

 holm, some observations of earth-currents, which were 

 measured on two lines, Stockholm-Goteborg and Sundsvall- 

 Stockholm. The measurements were performed from 

 minute to minute from oh. 40m. to 3h. 45m. a.m. (mid- 

 European time). The geographical coordinates for the 

 three places mentioned are the following : — 



Sundsvall ... ip-bz 23 N. ... \=\^ 19 E. from Greenwich 

 Stockholm ., 59 21 . . 18 < 



Gciieborg ... 57 42 ... 11 58 



The resistance of the line Stockholm-Goteborg was 2940 

 ohms, and that of the line Sundsvall-Stockholm 2336 ohms. 

 From the current-strengths measured in milliamperes we 

 obtain the potential differences expressed in millivolts per 

 km. by multiplication with r//, r indicating the ohm-resist- 

 ance of the line and ; the distance in km. from end to 

 end. For calculating the components of the potential 

 difference E.-W. (V) and N.-S. (V) we have the formulje 



V = 773>-3-32>' 

 \ ' = 0-8711 -I- 6bot', 



! and i' indicating the observed current-strengths on the 

 Stockholm-Goteborg and the Sundsvall-Stockholm lines. The 

 measured current-strengths proved considerably above the 

 normal at this time of day, though by no means reaching 

 to that of a magnetic storm. The two components, ex- 

 pressed in millivolts per km. (every fifteenth minute), are 

 as follows. The potential differences are considered posi- 

 tive in the directions E.-W. and N.-S. : — 



NO. 2123, VOL. 84] 



The greatest disturbances occurred shortly before and 

 after 2h. a.m. : V max.= -I-68.I, V max. = -|-56-6 millivolts 

 per km. D. Stenquist. 



E. Petri. 



Leptocephalus hyoproroides and L. thorianus. 

 In my paper " On the Occurrence of Leptocephali 

 (Larval .Mur;tnoids) in the .Atlantic West of Europe " 

 (Meddelelser fra Kommissionen for Havtindersogelser, 

 Serie Fiskeri, Bind iii.. No. 6, 1909, p. 12, PI. i.. Fig. 8, 

 PI. ii., Figs. 1-7), I have described and figured a hitherto 

 unknown Leptocephalus species under the name of Lepto- 

 cephalus hyoproroides, n.sp. It had escaped my attention, 

 however, that this name had already been employed by 

 P. Stromman in " Leptocephalids in the University Zoo- 

 logical Museum at Upsala," Upsala, 1896, p. 39, PI. iv.. 

 Figs. 5-6, for another form similar in habit, but differ- 

 ing quite definitely in several characters, e.g. the pigmenta- 

 tion and position of the anus, from the form described by 

 me. I would therefore propose that the name of the latter 

 should be changed to Leptocephalus thorianus, n.sp. (after 

 the Danish research steamer T/ior, on the cruises of which 

 the species in question was discovered). 



JoHs. Schmidt. 



Static Charge in Bicycl? Frame 

 While riding a bicycle recently I was overtaken by a 

 thunderstorm, and took shelter beneath a convenient tree 

 after propping the machine against a wall. When the 

 rain had ceased, in the course of about fifteen minutes, I 

 re-mounted, with my hands upon the handles in the usual 

 manner. The handles are of composition, resembling 

 vulcanite or a similar non-conducting material, the pedals 

 are shod with rubber, and the leather saddle completes the 

 insulation of the rider from the frame. Upon exchanging 

 my grip of one of the handles for the bar, I felt the effects 

 of a static charge which was sufficiently startling to 

 endanger equilibrium for the moment. I do not suggest 

 that the pneumatic tyre, which successfully insulates a 

 vehicle from the earth, adds a new terror to locomotion, 

 for even a timid rider in traffic would hardly be endangered, 

 but it would be interesting to know if this phenomenon 

 has been observed before, either on cycles or motor-cars. 

 Robert S. Ball, jun. 

 189 Gleneldon Road, Streatham, London, S.W., 

 July 2. 



