January 5, 1899] 



NA TURE 



235 



from the fact that it was but small over the greater part of the 

 Mediterranean, and so for long the deep-sea sailors of Europe 

 were without much experience of its effects. When it did force 

 itself on their notice it was supposed to be due to an error of 

 construction, and a correction was made so that the point 

 marked north on the card pointed to the astronomical north. 



The importance of Gilbert's " De Magnete " has only been 

 fully seen in the light of modern magnetic research. It con- 

 stituted in itself an advance which has not been equalled by any 

 single step during the three hundred years that have elapsed 

 since its publication. So far as observation and theory have 

 yet gone, even with the aid of Gauss's refined analysis, they 

 have only confirmed the conclusion there set forth, Magnits 

 niagiies ipse est g/ohtis terrcslris — " the earth is a great magnet." 

 It is of great importance to decide whether or not the earth is a 

 permanent magnet like a piece of steel, but the decision that its 

 magnetism is induced by currents of electricity will not in any 

 way contradict Gilbert's assertion. 



ilagnetic survey work has of course its own practical and 

 commercial importance, but in a country like America, where 

 public and private Vjoundaries have been laid down by the 

 compass, the determination of the secular variation is of peculiar 

 interest. Without it the results of early land surveys could not 

 now be interpreted. 



In all cases the earlier surveys in America were compass 

 surveys, and the directions referred to the magnetic meridian. 

 Hence, as the deviation of the magnetic from the true meridian 

 was known only in a few cases, the directions laid down in old 

 topographical maps and plans of estates can only be recovered 

 by determining the deviations now, and applying the known 

 value of the secular variation. And Dr. Bauer says that one of 

 the Eastern states actually still retains the magnetic meridian as 

 the legal meridian of reference for land surveys. We had 

 thought that such conservatism was unknown on the other side 

 of the Atlantic. 



Dr. Bauer quotes Robert Norman's own account of his 

 discovery of the dip.' It has been quoted before, but not many 

 have seen it, so we venture here to make a short extract. After 

 stating that he had repeatedly found needles which had been 

 finished and balanced before magnetisation inclining themselves 

 to the horizontal with the north pole down when magnetised by 

 being stroked with a lodestone, so that he had to " put some 

 small piece of wire on the south point, and make it equall 

 againe,"' but had put the result down to defect of construction 

 rather than to "anie such propertie in the .stone," he goes 

 on: " It chaunced at length that there came to my hands an 

 instrument to be made with a needle of sixe inches long, which 

 needle after I had polished, cut of a just length, and made it 

 stand levell upon a pin, so that nothing rested but onlie the 

 touching it with the stone ; when I had touched the same, 

 presentlie the north part thereof declined down in such sort that 

 being constrained to cut avvaie some of that part to make it 

 equall againe, in the end I cut it too short, and so spoiled the 

 needle wherein I had taken so much paines. Hereby being 

 stroken into some cholar, I applied myself to seeke further into 

 this effect. . . ." 



The first systematic .surveys were made by William Whiston, 

 better known perhaps as the translator of "Josephus." He 

 was active in carrying on magnetic observations with a view to 

 the determination magnetically of geographical position, and 

 first drew isoclinics, made relative intensity observations, and 

 invented the vibration method of obtaining the dip. His main 

 object was to obtain the prize offered for the best solution of the 

 problem of determining thi longitude at sea, and he seems to 

 have been successful in enlisting the interest of the Court, and 

 even in obtaining money grants in aid of his work. Although 

 the problem of the longitude was to be quite otherwise solved, 

 Whiston's researches were of very great value. From Whiston 

 to Gauss is a hundred years, but the next great development in 

 terrestrial magnetic science came when Gauss introduced abso- 

 lute measurement, and thus led observers to express results in 

 units independent of arbitrary constants, so that they were at 

 once available as data for other investigators. As a result the 

 .science has gone on vigorously from then till now developing 

 in interest and importance. This, of course, is only one part 

 of the effect of Gauss's work : it has been equally, if not more, 

 productive of progress in the science of pure and applied 

 electricity. 



With respect to the conduct of magnetic survey work gener- 

 I From his book, " The New .'ktlractive," &c., 1576. 



NO. 1523, VOL. 59] 



ally, Dr. Bauer makes some remarks which it would be well if 

 observers would bear in mind. Much time and labour has been 

 practically lost by the observation of only a single element, 

 such as the declination. As he says, fully 75 per cent, of the 

 time and money spent on a survey is spent in occupying stations, 

 and the remainder only in observation. Thus it is only a very 

 little further expense comparatively for an observer to observe a 

 little longer, and get with sufficient accuracy values of all three 

 elements. Thus magnetic declination surveys are of little value 

 by themselves, except for the land surveying application, and 

 those which have been carried out in many places could have 

 been rendered many times more valuable to science by a very 

 trifling additional outkiy. 



The initiation of terrestrial magnetic work by the British 

 Association, the magnetic surveys carried out in this country by 

 the British Association, and described in Sir Edward Sabine's 

 Report for 1861, the more recent elaborate surveys by Thorpe 

 and Riicker, and the work done in other parts of the world, are 

 all appreciatively referred to. 



Now that the British Association has again taken up the 

 work in a very special manner, and a magnetic committee has 

 been appointed, we may confidently expect to see a further 

 great development of the siibject. The work done by the 

 conference at Bristol, under the presidency of Prof. Ruck'er, is 

 a valuable instalment. A. Gray. 



PROGRESSIVE EDUCATIONS 

 'X'HE publication of the second and third volumes of the 

 .series of reports prepared for the Education Department 

 under the supervision of Mr. Michael E. Sadler, the Director 

 of Special Inquiries, again calls the attention of educationists 

 to the value of the work which is being performed by this latest 

 addition to our national machinery for the guidance and co- 

 ordination of educational effort. These reports, with their 

 predecessors, closely resemble in their scope the publications of 

 the U.S. Bureau of Education, and accentuate the fact that we 

 have only lately commenced to do what has been for .some 

 time the established custom in the States. Just as the man of 

 science acquaints himself with the work, failures and successes 

 alike, of previous investigators in the field of his own activity, 

 so to do the best possible work, the teacher, who is also an 

 experimenter, should similarly become familiar with what has 

 been accomplished by other teachers in different parts of the 

 world. With these reports to hand, and others which will 

 doubtless follow, there is no reason why the schoolmaster 

 should not, in the future, start the education of his pupils 

 armed with the experience of many successful veterans. 



Though every one of the 1389 pages included in these 

 volumes contains something of interest, this article is to be 

 concerned more especially with what there is to be learnt con- 

 cerning the present state of the teaching of science — whether in 

 this country or abroad. Of the many plans of treatment which 

 suggest themselves, perhaps, as reference to the volumes will be 

 thereby facilitated, it will be best to take the papers containing 

 important allusions to scientific instruction in the order in which 

 they occur in the volumes themselves. 



The London Polytechnic Institutes. 

 The London Polytechnic has but little resemblance to the 

 institutions to which a similar name is applied in France, 

 Switzerland, and Germany. Each Polytechnic Institute (of 

 which there are at present eleven, with four branches) is an 

 independent organisation which deliberately combines social 

 intercourse, recreation, and instruction. As educational institu- 

 tions these polytechnics constitute a new and distinct type : they 

 range from the "Upper Standard" day school for boys and 

 girls of thirteen, up to high University instruction and post- 

 graduate research. All kinds and grades of work go on 

 simultaneously. In one room boys of. twelve are learning 

 arithmetic, or girls of thirteen are being taught to sew ; in 

 another, classes of plumbers or bricklayers, compositors or 

 tailors, are being practically trained in the processes of their 

 respective crafts : close by is the smithy or the fitting shop, 

 crowded with young engineering artisans ; in other class-rooms 

 are groups reading Dante or studying economics ; and just at 

 hand are well-equipped physical and chemical laboratories where 



' " Speci.1l Reports on Educational Subjects." Vols. ii. and iii. (Issued 

 by the Education Department, 1898.) 



