i8o 



SCIENCE. 



[Vol. XIV. No. 345 



ents are represented to be no obstacle, sixteen inches in the yard 

 being practicable, and the descent at such an inclination is said to 

 be safe. No doubt the lovvness of the centre of gravity, which is 

 little more than two feet above the rails, will reduce the risk of run- 

 ning oft the track, but the enthusiastic recommendation of the sys- 

 tem by its promoters as peculiarly adapted for elevated railways in 

 cities would not be echoed, we think, by the dwellers and foot pas- 

 sengers in streets traversed by such a line. We do not see how a 

 continual shower bath is to be avoided, except by such an exten- 

 sive, expensive, and above all, opaque dripping pan as would both 

 require an immense expenditure and create an intolerable nuisance. 



— According to the Journal of Chemical Industry, the specific 

 gravity of glycerine when used for tempering steel or cast iron may 

 be varied between 1.08 and 1.26 at 15° C. by adding water, accord- 

 ing to the composition of the metal. The quantity of glycerine 

 should be from one to six times greater than the weight of the 

 pieces to be plunged into it, and its temperature may be varied 

 from 15° to 200° C, according to the hardness of the metal. The 

 harder the steel to be tempered, the higher should be the tempera- 

 ture of the glycerine. To increase the quenching power of the 

 bath various salts may be added. Thus, when a harder temper 

 is required, protosulphate of magnesia may be added in quan- 

 tity from one to thirty-four per cent of the liquid, or from one- 

 fourth to four per cent of sulphate of potassium. For a softer 

 temper one to ten per cent of chloride of manganese and one to 

 four per cent of chloride of potassium may be added. The princi- 

 pal advantages to be derived from these methods are : that the 

 temperature of the aqueous solution of glycerine may be varied 

 within wide limits, the boiling point of pure glycerine being 290° 

 C. ; and that, owing to the fact that solutions of glycerine dissolve 

 most salts that are soluble in water, the quenching properties may 

 be varied by readily dissolving in the bath such salts as suit the 

 kind of metal to be tempered and the degree of temper required. 



— The Gardeners' Chronicle reports that at the Paris Exposi- 

 tion many of the South American republics show specimens of 

 the product known locally as yerba de mate, or Paraguay tea, the 

 dried and broken leaves and stalks of different species of ilex. It 

 is exhibited in packets and in original bales of green hide. This is 

 the dietetic beverage of about 20,000,000 of people in South Amer- 

 ica, and its popularity is shown by the exhibits in the various pavil- 

 ions of the Argentine Republic, Paraguay, Uruguay, Brazil, Chili, 

 Bolivia, etc. It is difficult to get at any reliable returns as to the 

 entire traffic in this commodity, the production of which is carried 

 on in such a desultory and wide manner, and extends over so vast 

 an area of wild country where the holly-trees flourish. In the Ar- 

 gentine Republic the consumption is over thirty-five million pounds, 

 against five million pounds of coffee. In Paraguay the production 

 of mate is about five million pounds ; from Brazil there is an ex- 

 port of sixty-five million pounds to neighboring States, while the 

 local consumption is about half as much. This is singular in the 

 great coffee-producing centre of the world, which sends into com- 

 merce annually more than half the entire production of coffee. 

 Strong efforts are being made to open a trade with it in Europe, 

 especially in France, where shops advertise and recommend it. 

 Whether this will succeed remains to be seen, looking at the 

 increased production of tea, and the enormous increase in its sale 

 in Europe. Approaching in its chemical composition to coffee and 

 tea, it is asserted that it does not cause wakefulness or prevent 

 sleep. In the rural districts, as well as in the smaller towns, this 

 beverage is considered a regular form of diet, and not, like tea, a 

 mere accompaniment of the breakfast-table. It is sweetened with 

 sugar until it almost becomes a syrup. It is sold at from four to 

 eight cents per pound, and one pound will produce about twenty 

 quarts of infusion. It is sometimes flavored with cinnamon, 

 orange-peel, or lemon-juice. 



— At Cambridge, England, during the month of August, about 

 twenty elementary teachers were in residence for a brief visit at 

 Newnham College, and short courses of lectures were started in 

 history, literature, and physiology, which might serve as a useful 

 kind of university extension on a small scale. Full advantage was 

 taken of the interesting lectures in history, literature, physiology, 

 logic, and other subjects. The lecturers and students vied with 



each other in making their visitors' holiday as happy as possible, 

 arranging walking and boating excursions, impromptu concerts, 

 tea-parties, and other forms of entertainment for them. The so- 

 called old hall, the oldest of the three halls which now form the 

 college, was given up to the visitors, who were under the care of 

 two lady lecturers. The pretty rooms and tasteful decorations, the 

 quiet and beauty which form the charms of an academic life, will 

 doubtless be pleasant memories to those whose ordinary work lies 

 in less beautiful places. It has come to be understood that the 

 university extension gathering will in all probability take place an- 

 nually at Oxford. It appears that the facilities offered by the 

 place, such as the new schools, the general emptiness of the col- 

 leges, etc., are much greater than at Cambridge, and that the num- 

 ber of ladies attending these gatherings is likely to increase in 

 future years. As a means of drawing women together, and giving 

 an impetus to education, these meetings have already proved of 

 great value. They supply an enthusiasm and a desire for knowl- 

 edge and culture which can only be obtained by the gathering to- 

 gether of teachers and students. The , actual instruction giver> 

 can, of course, hardly be of consequence ; but for this purpose the 

 second part of the meeting, extending to the end of the month, 

 during which lecturers continued in greater detail the subjects 

 introduced during Part I., was probably found by the fraction of 

 students who remained for it to have considerable educational 

 value. Mr. Moulton, Mr. Mackinder, Professor Green, Mr. Chur- 

 ton Collins, Mr. Shaw, and Mr. Hewins were the lecturers, who 

 worked out in greater fulness the subjects which they had already 

 dealt with in a more summary fashion. This summer meeting at 

 Oxford was marked by an incident which may in time become 

 quite famous. The debating hall at the Union was for the first 

 time invaded by lady speakers. This is, indeed, a sign of the 

 times, which he who runs may read. Ip an audience of six hun- 

 dred a resolution in favour of women suffrage was carried by a 

 majority of three to one. The proceedings took place without of- 

 ficial sanction, and were tainted with the grossest illegality ; but 

 yet the roof did not fall, as doubtless it should have done had it re- 

 tained a scrap of reverence for the monastic traditions of old Ox- 

 ford. 



— An interesting series of experiments has recently been car- 

 ried out by the Dutch State railways, says Engineering, for the pur- 

 pose of ascertaining exactly the relative resistance of various pig- 

 ments to atmospheric changes and to the corrosive action of sea 

 water. The results have proved that the red-lead paints are less 

 affected by atmospheric influence than those which are composed 

 of the brown oxides of iron, on account of their adhering more 

 closely to the metal, and 6i their possession of greater elasticity. 

 It was also discovered that any sort of paint afforded an increased 

 protection if the plates were pickled in hydrochloric acid before its 

 application. The prevention of corrosion by salt water was found 

 to be possible by the admixture of the oxide of some electro- 

 positive metal, such as caustic lime and soda ; but the efficiency 

 of such a covering diminished when its alkaline properties had 

 been neutralized by the absorption of carbonic acid. Magnesia,- 

 however, was proved to be the most serviceable, seeing that it 

 does not absorb carbonic acid ; and not only does it protect the 

 iron from galvanic action, but it also does not affect the anti- 

 fouling qualities of the paint. 



— In the report just issued by the Oxford University Extension 

 delegates some interesting particulars are given, says the PalT 

 Mall Gazette, of the devotion to learning under difficulties which 

 some of the students display. Thus, at Camborne one of the stu- 

 dents was a miner, who, after the evening lecture, had to go in the 

 night shift underground. At Burnley, a weaver in a cotton-mill,' in 

 order to have more time for study, sacrificed her dinner-hour, and 

 remained at the loom reading between her hours of work. To 

 supplement the regular courses of lectures, and to carry on the 

 work therein begun, an increasing number of reading circles and 

 students', associations have, we see, been formed. Of the latter, 

 one of the most successful is at Exeter. It consists of ladies only, 

 and during the year it has held about twenty meetings for the dis- 

 cussion of literary subjects and the readings of essays, besides ar- 

 ranging for the delivery of ten special scientific lectures. The 



