440 



NA TURE 



\_Scpt. 9, 1880 



these precautions you need not fear failure, and you will 

 enjoy the spectacle so seldom seen, though so often 

 actually occurring, of hot water floating on the top of cold 

 water. 



It is almost as easy to demonstrate the fact that solid 

 bodies, such as wood, iron, and glass, expand when 

 heated. A steel knitting-needle, for example, is both 

 longer and thicker when hot than it is when cold. To 

 prove so minute a quantity as the increase in thickness 

 would require very del'ca'te apparatus indeed, but the 

 increase of length may be rendered visible by the follow- 

 ing simple arrangement given by Miss C. Martineau in 

 her capital " Easy Lessons in Heat." The knitting- 

 needle must be fixed firmly to the table by a table- 

 clamp (Fig. 13). Against the other extremity rests the end 

 of a straw to serve as an index or pointer. This straw, 

 which should be at least eight or nine inches long, is 

 transfixed by a pin at about a quarter of an inch above 

 the point where it touches the knitting-needle, the pin 

 being stuck into a block of wood or other substantial 

 support. The slightest movement of the end of the steel 

 needle will be rendered apparent by the movement of the 

 straw index. 



Another pretty experiment which is easily performed is 

 that of boiling water in a sheet of paper. Take a piece 

 of paper and fold it up, as schoolboys do, into a square 

 box without a lid, as shown in Fig. 14. Hang this up to a 

 walking-stick by four threads, and support the stick upon 

 books or other convenient props. Then a lamp or taper 

 must be placed under this dainty cauldron. In a few 

 minutes the -iiater will boil. The only fear is lest the 

 threads should catch fire and let the water spill into the 

 lamp and over the table. The flame must therefore not 

 be too large. A small taper will give a flame quite large 

 enough. The paper does not burn, because it is wet ; and 

 even if it resisted the wet it still would not burn through, 

 because the heat imparted to it on one side by the flame 

 would be very rapidly conducted away by the water on 

 the other. Another experiment of a similar nature, but 

 perhaps even more striking, is as follows : — Twist up the 

 edges of a common playing-card or other bit of cardboard, 

 so as to fashion it into a light tray. On this tray place a 

 layer of small shot or bits of lead, and heat it o\'er the 

 flame of a lamp. The lead will melt, but the card will 

 not burn (Fig. 15). It may be charred a little round the 

 edges, but immediately below the lead it will not be 

 burned, for here again the lead conducts oft' the heat on 

 one side as fast as it is supplied on the other. Lastly, we 

 gi\-e an experiment which, like the two preceding, proves 

 that a good conducting substance may protect a delicate 

 fabric from burning by conducting away the heat rapidly 

 from it. Lay a piece of muslin quite flat upon a piece of 

 metal. A live coal placed on the muslin will not burn it, 

 for the metal takes away the heat too fast. If the muslin 

 is however laid on a bad conductor, such as a piece of 

 wood, it will not be protected, and the live coal will 

 kindle the muslin. 



iTo be continued?) 



NOTES 

 The International Congress of Anthropology and Prehistoric 

 Archeology, wliich opens at Lisbon on t'ue 19th inst., promises 

 to be an interesting one. On the mornings of the 21st, 23vd, 

 25th, and 27th, questions relative to Portugal will be discussed — 

 Cut Flints of the Tertiary, Characteristics of the Paleolithic or 

 Quaternary Age, the Neolithic Period, Kitchen-middens, Sepul- 

 chral Caves, Age of Metals, &:c. Among the papers to be read 

 on the afternoons of these days are the follow ing : — M. Arcelin, 

 Antiquity of Man in the Valley of the Saone; M. E. Catailhac, 

 Recent Prehistoric Discoveries in the South of France; M. 

 Erne=,t Chantre, an Exploring Journey in the Caucasus ; M. 

 liildebr.ind, the State of Preliistoric Studies in Sweden; M. 



Schaffhausen, Prehistoric Man, &c. Sever.il intere.^ing excur 

 sions have been arranged fjr. Perhaps the most important 

 question to be brought before the Congress will be that of the 

 worked stones said to have been found by M. C. Ribeiro in the 

 Tertiary. The Local Committee have opened numerous cuttings 

 between Carregado and Cereal, and in that distance of twenty 

 kilometres it is stated that worked stones will be met with at 

 every step in the Miocene deposits. The railway companies of 

 Spain and Portugal will issue tickets at a reduction of one-half 

 to members of the Congress. 



At the approaching Congress at Edinburgh on October 6 to 

 13, the discussion on the first special question in the Educational 

 Department, "What maybe the dangers of educational over- 

 work for both sexes, with special reference to the higher class 

 of girls' schools, and tlie effects of competitive examinations ? " 

 will be opened with papers by Dr. Keiller, M.D., of Edinburgh, 

 and Miss Edith Peachey, M.D., of Leeds. Papers on the 

 second special question, " Plow far, and under what conditions, 

 ought the teaching of higher subjects in elementary schools to 

 form part of a system of national education?" will be contri- 

 buted by Sir George Campbell, K.C.S.I., and Dr. Robertson, 

 LL. D. Prof. Laurie will read a paper on the third special 

 question, "Is it desirable that public secondary schools should 

 be placed under local authorities and be subject to the super- 

 vision of the Committee of Council on Education?" 



We are glad to learn that Mr. Mnndella [intends, during his 

 sojourn on the Continent, to visit some of the principal foreign 

 technical schools. We have no doubt he will thus get some 

 enlightenment as to what real technical education means. 



The Geological Society of France have issued circulars 

 announcing that an extraordinary session will be held at 

 Boulogne, from September 9 to 19, under the presidency of 

 Prof. Gosselet of Lille, with an ample programme of papers 

 and excursions. 



At a meeting of delegates from local scientific societies, held 

 at Swansea on August 31, Mr. J. Hopkinson in the chair, vaiious 

 suggestions, principally with the view of securing a better re- 

 presentation of scientific societies at the meetings of the British 

 Association and a more intimate relationship between provincial 

 societies, were made, and the following resolutions were passed : — 

 I. That this Conference recommends that at future meetings of 

 the British Association it is desirable that the delegates from the 

 various scientific societies should meet, with the view of pro- 

 moting the best interests of the Association and of the several 

 societies represented. 2. That Mr. Hopkinson and Mr. Ford- 

 ham be a committee to carry out the views expressed at this 

 conference, and report to the conference of delegates to be held 

 at York in 1S81, in accordance with the foregoing resolution. 



To judge from the three volumes of its Bidletin which have 

 been sent us, the Philosophical Society of Washington seems to 

 produce some good work. The Society was founded ten years 

 ago, and the volumes embrace the period from 1871 to 18S0. 

 Tlie late Prof. Joseph Henry was the first president of the 

 Society, the object of which is stated to be the free exchange of 

 views on scientific subjects and the promotion of scientific inquiry 

 among its members. The following are a few of the papers con- 

 tained in the volumes before us :— " On the Adopted Value of 

 the Sun's Apparent Diameter," by Prof E. S. Holden; "On 

 the Delta of the Mississippi," by Prof. Forshey ; "On the 

 Zodiacal Light," by Prof. S. Alexander ; a detailed report on 

 the unusually brilliant meteor of December 24, 1873 ; a long and 

 elaborate memoir of Prof. Joseph Henry, w ith detailed notices 

 of his varied scientific work ; also the addresses he delivered during 

 his presidency; "On the ' Prodromus Method! Mammalium' 

 of Storr," by Mr. Theodore Gill ; a curious inquiry on the 



