November 4, 1897] 



NA TURE 



n 



report that there are 75 higher seajts of learning in Germany, 

 Austria proper, and Switreriand, having altogether 5963 profes- 

 sors, 67,062 students, and 6628 foreign students. There is in 

 (iermany one professor for I2*i students, and an average of 784 

 jirofessors and 926*3 students (of whom 67*2 are foreigners) to 

 one seat of learning. Austria has one professor for 117 students, 

 and an average of 80*5 professors and 949 4 students (of whom 

 o,\-\ are foreigners) to one higher seat of learning. Switzerland 

 has one professor for 5*9 students, and an average of 96 2 pro- 

 fessors and 569*6 students (of whom 208*3 ^^^ foreigners) to one 

 higher seat of learning. Among other subjects of articles in the 

 report are : the comparative study of popular education among 

 civilised nations ; education in France ; education in Mexico 

 and Central America; commercial education in Europe, particu- 

 larly in Austria, France, and Germany ; and the correlation of 

 studies. 



One of the most gratifying signs of educational progress is 

 the increasing efiSciency of technical institutions in the provinces 

 as well as in London. These schools are not only far better 

 equipped than they were a few years ago, but in many cases the 

 members of the teaching staffs are better qualified to impart in- 

 struction. The prospectuses and calendars which come before us 

 from time to time testify to a real development of facilities for 

 education in science and technology, and we are glad to observe 

 the advances which technical schools are making all over the 

 country. A prospectus just received from the Technical Col- 

 lege, Huddersfield, furnishes an instance of vahtable work being 

 done in a large technical college outside London. This college 

 provides full courses, both theoretical and practical, and of an 

 advanced type, in physics, chemistry, biology, art, engineering, 

 weaving and dyeing. There are also separate departments for 

 mathematics, languages ancient and modern, and commercial 

 subjects ; whilst a mining section is in process of formation. 

 Of especial importance is the fact that the college library con- 

 sists of some 10,000 volumes, an annual sum of 160/. being 

 devoted towards the purchase and binding of books, periodicals, 

 &c. At the present time an extension, calculated to cost about 

 13,000/., is being carried out. Improved accommodation will 

 thus be provided for chemistry and physics, and engineering ; a 

 room 105 feet by 27 feet has also been set aside for a museum for 

 biology and mineralogy. The number of students of both sexes 

 for the last two or three years averages about twelve hundred. 

 Students can at present take up at the college all the subjects 

 required by the London University for a degree in art or science, 

 and they will be able to continue to their D.Sc. work when the 

 new chemical and physical laboratories are completed. In all 

 departments we notice that practical work is carried on as well 

 as lectures. Dr. S. G. Rawson, the principal, appears to be 

 developing the college on the right lines, and Huddersfield will 

 doubtless benefit by the work he is doing. Financially the 

 college is also in a satisfactory condition. We think both 

 council and staff are to be congratulated upon the care and 

 energy which has been displayed in building up so strong and 

 useful an institution. 



SOCIETIES AND ACADEMIES. 



London. 



Physical Society, October 29.— Mr. Shelford Bidwell, Presi- 

 dent, in the chair. — Prof. Stroud exhibited and described the Barr 

 and Stroud "range-finder." The problem offinding the distance of 

 a given object at sea, or in the field, is complicated by shortness 

 of the trigonometrical " base," and by restrictions of time. .\s 

 a rule, the apparatus must be self-contained, and "snap-shot" 

 readings are obligatory, i.e. the range has to be determined 

 from a single instrument and from a single observation. At 

 3000 yards the errors must not exceed 3 per cent. In foggy 

 weather, or when viewing a nebulous object, this degree of 

 precision is difficult to attain, but under favourable circumstances 

 the authors have determined ranges, at that distance, within i 

 per cent, of accuracy. At shorter ranges measurement is more 

 exact ; thus an object at about 2000 yards may be estimated to 

 within about 12 yards. Prof. Stroud gave some account of the 

 history and of the general methods employed in these instru- 

 ments. Two images of the distant object, preferably of a line 

 such as a flag-staff, are received respectively upon two mirrors, 

 two lenses, or two prisms, placed one at each end of a fixed 

 support. From each ^of these, the light is then directed towards 

 the middle of the instrument, where the two images, after 

 further reflection, are viewed by one eye-piece. The optical 



NO. 1462. VOL. 57] 



system has finally to be adjusted so that the two images, as noW^ 

 seen in the eye-piece, lie in the same straight line. In the in- 

 strument designed by the authors this coincidence is attained by 

 translating a small prism parallel to the axis of the supporting 

 rod. The extent of this translation is a measure of the range. 

 Both eyes are used : the right for bringing the two images into 

 alignment; the left for "finding" the object through a small 

 field-glass, and for reading the scale of distances. At night, 

 sightings have to be taken from "points" of light, and as 

 these are unsuited for measurement, the authors convert 

 them into " lines " by the use of cylindrical lenses. 

 Various devices are introduced to prevent overlapping of the 

 images. The instrument is about five feet long, and tubular 

 in form ; it is made of copper, so as to have high thermal 

 conductivity to reduce differential heating. Within the 

 outer tube is the interior supporting rod, designed to equalise so 

 far as possible the effects of interior radiations. Several forms 

 of " separating " prisms were exhibited, the best for the purpose 

 consists of two " reflecting " prisms ; these receive the two rays 

 and direct both of them into a third prism, whose angle lies in 

 the space between the angles of the others. Mr. Barr drew at- 

 tention to the gimbal arrangement and the three struts that keep 

 the supporting rod centred in the tube. To give some idea of 

 the precision and scope of the range-finder, he observed that 

 they were there u^ing the equivalent of a 25-feet "circle," and 

 their measurements were comparable to the measurement of 

 20 sees, of angle on such a circle. The instrument is handled 

 by ordinary seamen, and stands rough usage on board ship for 

 years without injury. — Prof. Stroud then exhibited "a folo- 

 meter and spherometer." He explained that in determining 

 curvatures and focal lengths, some telemetric method was neces- 

 sary, and that, owing to want of parallelism of the beam, and 

 duplication of images, a short-focus telescope was always an in.- 

 efficient telemeter. For the measurement of inaccessible lengths 

 it was therefore better to use some simple form of "range- 

 finder." Such an apparatus could be made with a set of small 

 mirrors arranged in such a manner as to direct two images of 

 the distant object into an eye-piece, with a fixed prism in the 

 path of one of the incident beams. By sliding this instrument 

 along the optical bench one position could always be found at 

 which the two images, as seen through the eye-piece, 

 were in coincidence. He also described a method for 

 determining curvature by interposing a plate of plane glass 

 between the curved mirror and a source of light. — Mr. 

 Ackermann exhibited two experiments, (i) The blowing-out 

 of a candle-flame by the air from a deflating soap-bubble. The 

 ! bubble was blown at the mouth of an inverted beaker by breath- 

 I ing into a hole cut out at the top. This hole was then pre- 

 I sented to the flame^ and the flame was immediately quenched. 

 j But if the bubble was blown from ordinary air, with bellows, the 

 flame was merely deflected without being extinguished. (2) It 

 was shown that a miniature boat, provided with a false stern, 

 consisting of a linen diaphragm, could be propelled by filling 

 the hollow stern-space with ether, or with some liquid similarly 

 miscible with water. The motion is due to the continuous re- 

 lease of surface-tension behind the boat. Prof. Boys said that 

 when he tried, some years ago, to blow out a candle with a 

 soap-bubble filled with common air, he found the operation very 

 difficult — so difficult that, having once succeeded, he never re- 

 peated the attempt. It had not occurred to him, as it had to 

 Mr. Ackermann, that the COj present in the breath played a 

 part in the quenching. With regard to the second experiment, 

 he had seen a small boat propelled by dissolving camphor astern, 

 but he thought the use of a liquid for that purpose was a novelty. 

 — The President proposed votes of thanks, and the meeting was 

 adjourned until November 12. 



P.^RIS, 



Academy of Sciences, October 26.— M. A. Chatin in the 

 chair. — Apparatus for measuring the altitudes attained by bal- 

 loons. Verification of the results furnished by barometers, by 

 M. L. Cailletet. The dial of the aneroid is placed exactly in 

 the focus of a photographic camera, to which such a mechanism 

 is fitted that every two minutes two photographs are taken 

 simultaneously, one of the barometer and another of the 

 earth. From the focal length of the photographic ob- 

 jective, the distance of any two points on the earth, and 

 the distance of these two points on the negative, the calculation 

 of the true height is easily calculated. The apparatus worked 

 perfectly in a preliminary balloon ascent made by MM. Hermite 

 and Besan9on. — Report on a memoir of M. Hadamard, entitled 



