io8 



NATURE 



[November 19, 1914 



of the underspin and the dynamics of the slice 

 and the pull are as if they wee not. There is no 

 "science" in the book; but it is admirably human. 



C. G. K. 



A History of the Teaching of Domestic Economy. 

 Written for the Association of Teachers of 

 Domestic Subjects in Great Britain by Ailsa 

 Yoxall. Pp. 58. (London : Knapp, Drewett 

 and Sons, Ltd., n.d.) Price 6d. 

 This little book represents the first attempt to 

 place on record an account of the j^^rowth of the 

 teaching of domestic economy in Great Britain. 

 The movement appears to have been started in 

 earnest about 1840, when some instruction in 

 needlework began to be given in national schools 

 for girls and infants. From this date to the 

 present time the importance of instruction of this 

 character has been recognised increasingly, until 

 to-day the Association of Teachers in Domestic 

 Subjects includes no fewer than thirteen important 

 local branches, receives direct recognition by 

 the Government, and elects one of its members 

 to represent it on the Registration Council. The 

 subject is now also given a more scientific char- 

 acter and includes a practical and theoretical study 

 of every aspect of housewifery. The book de- 

 serves the attention of all who are interested in 

 vocational education for girls. 



LETTER TO THE EDITOR. 



IThe Editor does not hold himself responsible for 

 opinioJis expressed by Jiis correspoudeiiis. Xeiilwr 

 can he undertake to return, or to correspond with 

 the writers of, rejected manuscripts intended for 

 this or any other part of Nature. No notice is 

 taken of anonymous comniunications.] 



Newton and the Spectrum. 



In* Nature of November 5, 1914, p. 263, I notice 

 in the Astronomical Column a statement to the effect 

 that, in connection with spectrum analysis, WoUastoi 

 (1802) was the first to employ the slit. I therefon 

 venture to send a copy of the following passage, con- 

 tributed by me to the 1913 Journal of the Leeds Astro- 

 nomical Society, published last September : — 



"Almost all writers, who quote Newton's classical 

 experiment, overlook or ignore the fact that, recog- 

 nising the impurity of the spectrum formed by admit- 

 ting the sunlight through a round hole, Newton sug- 

 gested the use of a linear aperture. Here is the 

 passage from pp. 59-60 of the 4th edition of the 

 Opticks (Book I., Prop. IV.) :— 



" ' Yet instead of the Circular Hole, 'tis better to 

 substitute an oblong Hole shaped like a long Parallelo- 

 gram with its Length parallel to the [refracting edge 

 of the] Prism. For if this Hole be an Inch or two 

 long, and but a tenth or a twentieth Part of an Inch 

 broad, or narrower; the Light of the Image will be as 

 simple as before, or simpler, and the Image will 

 become much broader, and therefore more fit to have 

 Experiments try'd in its Light than before.' 



" It is not quite clear whether Newton actually tried 

 this narrow aperture. I think he did; and it is in- 

 teresting to consider that, if he bad sufficiently nar- 

 rowed the slit, and observed the spectrum directly by 

 the eye, instead of observing it upon a screen, he 

 might have discovered the dark lines." 



C. T. Whitmei.i.. 



Invermay, Hyde Park, Leeds, November 9. 



NO. 2^^ I. VOL. QaI 



THE PARTLAL STER I LTS ATION OF SOILS. 



rHE work to be described in this article arose,, 

 as so often happens, out of an accident in 

 the laboratory. The writer was investigating the 

 rate of oxidation of phosphorus, and during th? 

 progress of the work was called to take charge of 

 an agricultural laboratory. Before finally dis- 

 banding the apparatus some observations wer^ 

 made on soils, and it was found that fertile soils 

 absorbed oxygen more rapidly than non-fertile 

 soils of the same character. Since the action was. 

 very considerably reduced in sterilised .«:oils it 

 was concluded that the process is largely due to 





Partially sterilised soil 

 (by toluene). 



Untreated 

 .^oil. 



r <-. 



Pariiallj -■t. r lised soil 

 (by carbon disulphide). 



Fig. I. — Crops grown on untreated and in partially sterilised soils. 



the activity of micro-organisms, and the connec- 

 tion between oxygen absorption and fertility was 

 attributed to the large part played by micro- 

 organisms in the production of plant food. 



In doing the final confirmatory set of experi- 

 ments the soils were only sterili.sed at 100° and 

 not at 130°, in consequence of a mistake which 

 caused some little annoyance at the time. An 

 experiment was, however, carried out with this 

 partially sterilised soil, and it led to the remark- 

 able result that oxygen absorption is more rapid 

 in such soil than in normal untreated soil. Other 

 methods of partial sterilisation gav6 the same 

 result. In view of the close connection between 



