>96 



NATURE 



[July 30, 1896 



where over ;ri'io,ooo has been spent on scientific equipment, 

 science is not a compulsory subject ; and, in fact, it is practically 

 impossible to get science teaching on the classical side. 



It would be interesting to know how far science is compulsory 

 in the various public schools. I have no doubt there are others, 

 but I only know of two— Eton and Clifton — where it is. 



" A Parent." 



Discharge of an Electrified Body by Means of the 

 Tesla Spark. 



It has been shown that a body charged with electricity may 

 be discharged by means of the rays from a Riintgen bulb. I 

 find, also, that an electrified body is rapidly discharged by the 

 influence of a high-frequency spark, such as that produced by the 

 Tesla apparatus. The discharging action was shown in this way. 

 A high-frequency spark was produced between two rather blunt 

 points, one inch apart in air, no bulb being used. A gold-leaf 

 electroscope, placed far away from the influence of the spark, was 

 used to test the electrical condition of the charged bodies — viz. a 

 stick of sealing-wax and a rod of glass. The sealing-wax was 

 rubbed, and the electroscope indicated that it was well charged. 

 It was again rubbed, and then brought to within a foot of the 

 points, and by means of a key in the battery circuit the Tesla 

 coil was thrown into action for an instant. On testing the 

 sealing-wax rod with the electroscope, it was found to be en- 

 tirely discharged. A similar experiment was next made with a 

 glass rod ; the glass rod was entirely discharged by the Tesla 

 spark. From a previous experiment, it was seen that the 

 electrification of the rods was dissimilar. The influence, then, 

 of the high-frequency spark is to discharge electricity of either 

 sign. Frederick J. Smith. 



Oxford, July 17. 



On the Occurrence of the Pelagic Ova of the Anchovy 

 off Lytham. 



Hitherto no free eggs of this species have been procured in 

 Britain, though Mr. Jackson found ripe'females off Southport 

 in June 187S. Day observes, in the " Brit. Fishes," that the 

 anchovy spawn off our coasts in September and December ; 

 though in June specimens have been found with enlarged ova, 

 and so tender that they burst on the slightest interference. On 

 June 26 last, however, Mr. R. L. Ascroft, of Lytham, obtained 

 certain ova in the tow-nets used oft" Lytham Pier, which he 

 courteously sent for examination in a solution of formalin. These 

 eggs agree in all respects with the descriiitions and figures of 

 Hoffman, Wenckebach, and Raffaele, though somewhat larger. 



Prof. Hoffman found that the anchovies of the Zuyder Zee 

 were ripe in the monthsof June and July, and that the eggs were of 

 an oval form, and about i mm. in length. In July lSS6, Wencke- 

 bach captured the same eggs in his tow-nets, and hatched them 

 on the third day. The egg is ovoid, and the yolk reticulated as 

 in other clupeoids, such as the sprat. Raffaele procured the 

 same egg at Naples— from May to September — and also ascer- 

 tained that hatching took place after two or three days. He 

 gives the long diameter of the egg as 1-15 to 1-25 mm., and the 

 shorter at 0-5 to 0-55 mm. The larva is provided with a 

 reticulated yolk of little depth, but of great length, extending, 

 indeed, considerably beyond the middle of the body, while the 

 notochord is unicolumnar. In two or three days after hatching 

 the yolk had greatly diminished, the pre-anal fin-membrane was 

 augmented, and the dorsal had likewise passed much further 

 forward. The buccal aperture had also opened, and four 

 branchial arches were visible. The yolk had completely dis- 

 appeared about the fourth or the fifth day, and pigment occurred 

 in the eye and along the dorsum. The post-pyloric portion of the 

 gut was transversely ridged. 



The eggs sent by Mr. Ascroft were, for the most part, advanced ; 

 the embryo occupying the long a.\is of the egg, as usual in such 

 cases, and as shown by Raffaele. The long diameter ranged 

 from I "295 to I "447 mm., the shorter diameter being almost 

 constant at 0'685 mm. ; they are thus larger than those from 

 the Mediterranean and the Zuyder Zee. 



Interesting accounts of the occurrence of anchovies off the 

 British shores have been given by Prof Ewart and Mr. Cun- 

 ningham, and they would seem to be by no means so rare as 

 at one lime supposed. Prof. Hoffman thought that very rapid 

 growth occurred during the first year of the life of the anchovy, 

 so that those spawned in June and July reached a length of 

 12 cm. at the end of October, and Dr. Hoek appeared to agree 

 with him, Ehrenbaum, however, asserts that the young anchovies 



NO. 1396, VOL. 54] 



referred to are in their second year ; and this would be more in 

 harmony with what is known of the herring, the pilchard, and 

 the sprat. This author considered that the anchovy breed'; 

 when two years old. W. C. M. 



Gatty Marine Laboratory, St. Andrews, July 16. 



Information on Scientific Questions. 



Dr. Brown Goode is quoted in Nature of July 16 

 (p. 252), as saying "he cannot think of any scientific 

 subject regarding which a letter, if addressed to the scientific 

 bureaus in Washington, would not receive a full and practical 

 reply." I infer from this that the replies are prompted by the 

 courtesy of the officers of the various departments, and that the 

 public of the United States possess no right to demand them. 

 If this is so, surely Dr. Brown Goode's scoft' at British Govern- 

 ment departments is disingenuous, to say the least of it. 



But though we have no right to apply for information to 

 Government departments, it must have been the experience of 

 great numbers of people that information may be most readily 

 obtained, and that only very exceptionally does a public officer 

 fail to reply to any reasonable inquiry relating to his own branch 

 of science — or art. I have myself made frequent inquiry of 

 officers of the British Museum, both at Bloomsbury and South 

 Kensington, and in every case (save one) have had courteous 

 and satisfactory replies from those to whom my inquiries were 

 addressed. I have received similar treatment from the Depart- 

 ment of Science and Art, from the .Society of Antiquaries, from 

 the Board of Trade, from the Agricultural Department, from the 

 Royal Academy, from the School of Mines, and from other 

 bodies which, though in this country they are of a pseudo- 

 private character, would in the States probably come under 

 some public department. 



It may be that the experience of others has been less favour- 

 .able than mine ; but this I find it difficult to believe, and unless 

 Dr. Brown Goode means us to understand that the Washington 

 bureaus may be peremptorily applied to for information, it 

 would be seemly to withdraw the implied charge of discourtesy 

 which he has levelled at our public officers. 



I would further point out that in many of our country towns 

 and cities there exist municipal museums, to which local inquiries 

 are first addressed, whence information may be obtained, at, I 

 confess, considerable inconvenience to the curators. I have 

 myself had inquiries on all sorts of questions from agriculturists, 

 medical men, colonists, genealogists, artificers, trade.smen, 

 youthful collectors, and the general public, some of which have 

 taken me two or three hours, and occasionally a microscopic 

 examination of specimens, to solve, and doubtless many other 

 persons could tell of similar experiences. It is quite remarkable 

 how entirely the public have adopted the view that a curator of 

 a museum is a fit and proper person to consult upon any and 

 every subject ; but my experience leads me to think that curators 

 have brought this condition of things upon themselves. 



Exeter, July 20. James Dallas. 



Horary Variation of Meteors. 



Dr. Doberck, of whose paper an interesting abstract was 

 given on June 25, informs us that shooting-stars decrease in 

 average magnitude from evening to morning, their duration and 

 length of path decreasing with the magnitude, while the velocity 

 increases as the magnitude diminishes. 



This larger evening magnitude is said to be " owing to the 

 fact that the meteorites are heated to incandescence nearer the 

 earth in the evening than in the morning," a fact deserving 

 further explanation. 



In the morning we stand on the front of the earth in her 

 orbital motion ; the earth then generally meets the meteors 

 with the double velocity of their two motions. In the 

 evening the meteors are overtaking the earth with a slower 

 motion, the difference of their velocities. In the morning, there- 

 fore, the meteors enter the atmosphere with double velocity, and 

 are burned up before nearly reaching the earth. In the evening, 

 the slower motion enables them to penetrate further through the 

 atmosphere before becoming incandescent. 



So also most aerolites fall in the evening hours, although 

 shooting-stars are most numerous in the morning. 



The impalpable air shields the earth from those meteorites 

 whose impact would be dangerous, burning them up by their 

 very velocity, while giving passage to those vvhose slower motion 

 renders them comparatively harmless. G. C. BoMl'AS. 



London, July 18. 



