July i8, 1901] 



NATURE 



291 



pass over the events which led to the change of site from the 

 Old Deer Park at Richmond to Bushy. It is sufficient to say 

 that at present Kew Observatory in the Deer Park will remain 

 as the Observatory department of the Laboratory, and that most 

 of the important verification and standardisation work which 

 in the past has been done there will still find its home in the 

 old building. 



Bushy House was originally the official residence of the Ranger 

 of Bushy Park. Queen Anne granted it in 1710 to the first Lord 

 Halifax. In 1771 it passed to Lord North, being then probably 

 rebuilt. Upon the death of Lord North's widow in 1797, the 

 Duke of Clarence, afterwards William IV,, became Ranger ; after 

 his death in 1S37 it was granted to his widow, Queen Adelaide, 

 who lived there until 1849. At her death it passed to the 

 Due de Nemours, son of King Louis Philippe, and he resided 

 there at intervals until 1896. 



In spite of this somewhat aristocratic history, it will make 

 an admirable Laboratory. A description of the Laboratory, with 

 illustrations, will be found in Nature, vol. Ixiii. p. 300. 



The floor space available is much less than that of the Reichs- 

 anstalt. But size alone is not an unmixed advantage ; there is 

 much to be said in favour of gradual growth and development, 

 provided the conditions are such as to favour growth. Person- 

 ally I should prefer to begin in a small way if only I felt sure 

 I was in a position to do the work thoroughly, but there is 

 danger of starvation. Even with all the help we get in freedom 

 from rent and taxes, outside repairs and maintenance, the sum 

 at the disposal of the committee is too small. 



Science is not yet regarded as a commercial factor in Eng- 

 land. Is there no one who realises the importance of the 

 alliance, who will come forward with more ample funds to start 

 us on our course with a fair prospect of success ? One candid 

 friend has recently told us in print that the new institution 

 is on such a microscopic scale that its utility in the present 

 struggle is more than doubtful. Is there no statesman who can 

 grasp the position and see that with, say, double the income 

 the chances of our doing a great work would be increased a 

 hundredfold ? 



The problems we have to solve are hard enough ; give us 

 means to employ the best men and we will answer them, starve 

 us and then quote our failure as showing the uselessness of science 

 applied to industry. 



There is some justice in the criticism of one of our technical 

 papers. I have recently been advertising for assistants, and a 

 paper in whose columns the advertisement appears writes, " The 

 scale of pay is certainly not extravagant. It is, however, possible 

 that the duties will be correspondingly light." 



Now let me illustrate these aims by a more detailed account of 

 some of the problems of industry which have been solved by 

 the application of science, and then of some others which remain 

 unsolved and which the Laboratory hopes to attack. The story 

 of the Jena Glass Works is most interesting ; I will take it first. 



An e.xhibition of scientific apparatus took place in London 

 in 1876. Among the visitors to this was Prof. -Abbe, of Jena, 

 and in a report he wrote on the optical apparatus he called 

 attention to the need for progress in the art of glass making if 

 the microscope were to advance, and to the necessity for 

 obtaining glasses having a different relation between dispersion 

 and refractive index than that found in the material at the dis- 

 posal of opticians. Stokes and Harcourt had already made 

 attempts in this direction, but with no marked success. 



In 1881 Abbe and Schott, at Jena, started their work. Their 

 undertaking, they write five years later in the first catalogue of 

 their factory, arose out of a scientific investigation into the con- 

 nection between the optical properties of solid amorphous fluxes 

 and their chemical constitution. When they began their work 

 some six elements only entered into the composition of glass. 

 By 1888 it had been found possible to combine with these, in 

 quantities up to about 10 per cent., twenty-eight different 

 elements, and the effect of each of these on the refractive index 

 and dispersion had been measured. Thus, for example, the in- 

 vestigators found that by the addition of boron the ratio of the \ 

 length of the blue end of the spectrum to that of the red was 

 increased ; the addition of fluorine potassium or sodium pro- 

 duced the opposite result. 



Now in an ordinary achromatic lens of crown and flint, if the 

 total dispersion for the two be the same, then for the flint glass 

 the dispersion of the blue end is greater, that of the red less 

 than for the crown ; thus the image is not white, a secondary 

 spectrum is the result. 



NO. 1655, VOL, 64] 



Abbe showed, as Stokes and Harcourt had shown earlier, 

 that by combining a large proportion of boron with the flint its 

 dispersion was made more nearly the same as that of the crown, 

 while by replacing the silicates in the crown glass by phosphates 

 a still better result was obtained, and by the use of three glasses 

 three lines of the spectrum could be combined ; the spectrum 

 outstanding was a tertiary one, and much less marked than that 

 due to the original crown and flint glass. The modern micro- 

 scope became possible. 



The conditions to be satisfied in a photographic lens differ from 

 those required for a microscope. Von Seidel had shown that 

 with the ordinary flint and crown glasses the conditions for 

 achromatism and for flatness of field cannot be simultaneously 

 satisfied. To do this we need a glass of high refractive index 

 and low dispersive power, or vice versa ; in ordinary glasses 

 these two properties rise and fall together. By introducing 

 barium into the crown glass a change is produced in this 

 respect. For barium crown the refractive index is greater and 

 the dispersive power less than for soft crown. 



With two such glasses, then, the field can be achromatic and 

 flat. The wonderful results obtained by Dallmeyer and Ross in 

 this country, by Zeiss and Steinheil in Germany, are due to the 

 use of these new glasses. They have also been applied with 

 marked success to the manufacture of the object glasses of large 

 telescopes. 



But the Jena glasses have other uses besides optical. " About 

 twenty years ago " — the quotation is from the catalogue of the 

 German exhibition — " the manufactureof thermometers had come 

 to a dead stop in Germany, thermometers being then invested 

 with a defect, their liability to periodic changes, which seriously 

 endangered German manufacture. Comprehensive investiga- 

 tions were then carried out by the Normal Aichungs Commission, 

 the Reichanstalt and the Jena Glass Works, and much labour 

 brought the desired reward." 



The defect referred to was the temporary depression of the 

 ice point which takes place in all thermometers after heating. 

 Let the ice point of a thermometer be observed ; then raise 

 the thermometer to, say, 100°, and again observe the ice point 

 as soon as possible afterwards ; it will be depressed below its 

 previous position. In some instruments of Thuringian glass a 

 depression of as much as o"'65 C. had been noted. For scientific 

 purposes such an instrument is quite untrustworthy. If it be 

 kept at, say, 15" and then immersed in a bath at 30", its reading 

 will be appreciably different from that which would be given 

 if it were first raised to, say, 50', allowed to cool quickly just below 

 30°, and then put into the bath. This was the defect which the 

 investigators set themselves to cure. 



Table I. gives some details as to thermometers. 



Table L 

 Depression of Freezing Point for various Thermometers. 



Weber had found in 1883 that glasses which contain a mixture 

 of soda and potash give a very large depression. He made 

 a glass free from soda with a depression of o°'l. The work 

 was then taken up by the Aichungs Commission, the Reichs- 

 anstalt and the Jena factory. W'eber's results were confirmed. 

 An old thermometer of Humboldt's, containing o'86 percent, of 

 soda and 20 per cent, of potash, had a depression of o" '06, while a 

 new instrument, in which the percentages were 127 per cent, 

 and I0"6 per cent, respectively, had a depression of o''65. 



An English standard, with 15 per cent, of soda and 12-3 per 

 cent, of potash, gave a depression of o°l5, while a French 

 "verre dur" instrument, in which these proportions were 

 reversed, gave only o°o8. 



It remained to manufacture a glass which should have a low 



