546 



NATURE 



[OCTOBEK 5, 189; 



sun, and two days' walk in a suffocating heat, he happened to 

 be in a room with several other persons, [and during conversa- 

 tion looked at a balcony bathed in bright sunlight, but without 

 taking any special interest in it. The balcony was decorated 

 with trellis-work and ivy. Flowering creepers were arranged 

 in vertical columns, each column being crossed below by the 

 iron bars of the balcony, and above by sticks supporting the 

 plants. A cage with birds hung up in the middle. Two days 

 afterwards, very early in the morning, the professor was in bed, 

 bat perfectly awake, and in ordinary health, when, to his 

 astonishment, he saw on the ceiling, by the light coming through 

 Venetian blinds of two l.ir^e windows, an exact reproduction, 

 in all its colours and details, of the balcony referred to. The 

 phenomenon lasted long enough to permit some detailed in. 

 vestigation. On closing the eyes, the image disappeared, to 

 appear again when they were opened. It was unaffected by 

 regarding it with each eye alternately. A finger placed betwee . 

 the eye and the image intercepted it in the same manner as it 

 would any ordinary object ; in short, the phenomenon obeyed all 

 the optical laws of vision. And not only was the cage of birds 

 reproduced, bat also its swinging motion noticed before. Prof. 

 Vignoli argues that this cannot have been a case of ordinary 

 hallucination, since the latter is unaffected by the opening or 

 closing of the eyes, and is practically limited to occasions of 

 abnormal health or disturbed state of mind. It must be re- 

 garded as an outward projection of a recollected image, though 

 the mechanism of this projection does not appear to be well 

 understood by the professor himself. A case such as this, of 

 what the German psychologists wouU call wach-ti-aum, merits 

 the attention of those interested in psycho-physics. 



- The current number of the Electrical Review contains a 

 description of some of the latest appliances in " electric heat, 

 ing " for domestic use. In the cookery experiments at the 

 Crystal Palace last year the efficiency obtained was, as a rule, very 

 small, and the wires used in the apparatus were soon destroyed. 

 Mr. Binswanger, of the General Electric Company, claims to 

 have got over both these drawbacks, as.w'ell as that of the diffi- 

 culty of insulation. Instead of wrapping the wires in asbestos, 

 mica, &c. (under which conditions they rapidly oxidise), or 

 clothing them with enamel (which cracks at high temperatures), 

 a cement is applied in a cold state, which is said to insulate well 

 without cracking, even at very high temperatuies. The " elec- 

 tric kettle " has a copper bottom resting on a double layer of 

 silicate cement, between the two parts of which the copper wires 

 carrying the current are arranged. The I pint size takes 3 

 amperes at 100 volts to raise the water to boiling, and as the 

 time required to raise a pint of water Itom 15° C. to 100 C. by 

 an expenditure of 1000 watts is 37 minutes, this kettle, which is 

 a " 300-watt kettle," will take 12 minutes to boil I pint. With 

 electricity at 4d. per unit, the cost of boiling the pint of water 

 would be approximately one farthing, which is, of course, much 

 dearer than gas. -Stew-pans, ovens, and "radiators" for heal- 

 ing rooms are also made, as well as frying-pans and gridirons, in 

 the two last-named of which greater economy is practicable 

 than in the other cases, as llie heat can be produced in the exact 

 spot in which it is wanted. Altogether it is evident that 

 although the use of "elcciric heating" for domestic culinary pur. 

 poses is not yet in its really practical stage, it is well on the way 

 there. 



I.N the course of an interesting series of articles in 

 Elcctricili on the " Electric Lighting of Trains," we find the 

 following figures given as a comparison between the cost of oil- 

 lamps and electric lights. The system under discussion is that of 

 accumulators carried in the train and charged at fixed charging 

 stations. The total expense of an electric-lamp in a first-class 

 carriage, including interest on capital, &c., comes out at 0'0289 



NO. I2JLQ. VOL. 4.8] 



francs per " lamp-hour," while an oil-lamp (of only 7-candle 

 power) comes to 038 francs per hour, while in the second and 

 third class carriages, where more lamps are run off the same 

 battery, the comparison is still better in favour of the electric 

 system. 



A CATALOGUE of works on Phanerogams, Talphabetically 

 arranged in genera, has been issued by Messrs. Dulauand Co. 



Two pamphlets by Sir Spencer Wells h.ave been sent to us — 

 one, "The Prevention of Preventible Disease," is a lecture 

 delivered in Glasgow in May last, and the other, "Cremation 

 and Cholera," is reprinted, with additions, from the Forum 

 for February, 1893. They both deserve a wide circulation and 

 attentive reading. 



Messrs. Casseli, and Co. have just published a new edition 

 of " Elementary Lessons with Numerical Examples in Practical 

 Mechanics and Machine Design," by R. G. Blaine. The book 

 has been to a large extent rewritten, and contains a good deal 

 of additional matter, an attempt having been made to bring the 

 work up to date. 



There is little of scientific value in Mr. Phil Robinson's latest 

 volume — " Some Country Sights and Sounds " (Unwin). The 

 author, however, writes pleasantly enough on a variety of topics 

 more or less to do with the country. 



We have received a volume containing the meteorological 

 observations made at the Adelaide Observatory and other 

 places in South Australia and the northern territory, during the 

 years 1884-5, under the direction of Sir Charles Todd, F.R.S. 



A new edition (the eighth) of Valentin's "Course of 

 Practical Chemistry, or Qualitative Chemical Analysis," edited 

 and revised by Prof. W. R. Hodgkinson, has just been published 

 by Messrs. J. and A. Churchill. .\ few additions have been 

 introduced into the work, including an extra chapter, in which 

 quantitative operations are dealt with. 



The June nuMiber of Timehri, the journal of the Royal Agri- 

 cultural and Commercial Society of British Guiana, has just 

 appeared, and contains articles on "The Seasons in Guiana," 

 " Notes on a Journey to a Portion of the Cuyuni Gold Mining 

 District," and "Amateur Insect Collecting in British Guiana," 

 occasional notes, reports of the society's meetings, &c. It may 

 be obtained in London from Mr. Stanford. 



Messrs. Blackie and Son have just published an attractive 

 little book entitled "Animal and Plant Life," by the Rev. 

 Theodore Wood. The book is the sixth number of a useful 

 series of science readers adapted for use in elementary schools. 



" Weissmann's Theory of Evolution "(1893) is the title of an 

 article by Prof. Romanes in The Open Court of September 14. 

 Prof. Weismann's recent modifications of his sequent theory of 

 evolution are the chief points discussed. 



A LIST of Coleoptera, prepared by Mr. James Edwards, ami 

 forming Part XII. of the "Fauna and Flora of Norfolk," ha* 

 been reprinted from the Tiansactions of the Norfolk and 

 Norwich Naturalists' Society (Vol. V.), and issued separately. 



Under the title " Les Moleurs a Gaz et a Petrole " (Gau- 

 thier Villars), M. Paul Vermand gives an excellent summary of 

 the present state of knowledge of atmospheric motors. The' 

 volume belongs to the Aide-Memoire series, .\nother work in 

 the same series that has recently been received is " Decoration 

 Ceramique au Feu de Moufle," by M. E. Guenez. 



Messrs. Methuen and Co.'s Commercial Series," intended 

 to assist students and young men prepaiing for a commercial. 



