310 SUMMARY OF CURRENT RESEARCHES RELATING TO 



averaged 1/833 in. in diameter, while ten ditto from a two-ply No. 28 

 worsted yarn averaged 1/833 in. Both yarns were from one spinner 

 and both (as was afterwards discovered) made of three-eighths blood 

 wool, which fact explains the exact correspondence in diameter as above. 



The superintendent of one of the largest mills in New England 

 uses the camera lucida for microscopic measurement of fibres, by a 

 method effecting great saving of time and eyesight. His mill sorts wool 

 into eight different sorts, and he states a good sorter has no difficulty 

 in determining one quality from another, wherein the difference as 

 between two sorts is measured by less than 1/1000 in. in average 

 diameter of fibres, which fact he has determined with the Microscope. 

 A large establishment giving him a sample of foreign cloth to dupli- 

 cate, lie ascertained by the camera lucida method the quality of wool in 

 both warp and weft threads, and knowing from previous records the 

 measurements of his own mill's sortings of wool, was thus enabled to 

 pick out from stock on hand what would give, when worked up, a 

 practical duplicate of the foreign fabric. 



The condition as to health or disease in wool fibres, the freedom from 

 or appearance of previous manipulation (as in shoddy yarns), the 

 lumpiness apt to prevail in yarns constituted largely of noils (fine waste 

 stock), the adulteration of yarns by the smuggling of cheaper materials 

 into wool, silk, &c. (the Microscope led to detection of fifteen per cent, 

 cotton in a so-thought worsted yarn), the source of foreign matters 

 found on the face of cloth, as discovered when dyed, whether cotton off 

 the spinning machinery or flax from the twine of the wool-sacks, or 

 grasses from the sheep pastures, all these are matters largely deter- 

 minable through the use of the Microscope, which it is considered will 

 be more and more generally employed in textile industries, as competi- 

 tion becomes intense and general culture advances. 



The writer concludes : — " As to the use of the Microscope on made- 

 up goods this is microscopy in the gross, and is, I fancy, mainly confined 

 to thread-counting. Consult some maker of fine cassimeres. A woman 

 with a fifty-cent thread-counter can, I take it, distinguish much better 

 as to the quality of two pieces of muslin or linen, by simply counting 

 the threads to the quarter-inch, than she could by feel or naked eye." 



Value of the Microscopic Analysis of Rocks.* — M. A. Eenard in a 

 lecture at the Royal Institution said : — " Our knowledge of eruptive 

 rocks came to be enriched in an unexpected manner by the application 

 of the Microscope to lithology. We need not here recall the almost 

 marvellous results obtained by this method of investigation, inaugurated 

 by Mr. H. C. Sorby, but we may say, in a word, that the microscopic 

 analysis of rocks has changed the face of petrography. Let us confine 

 our attention to some of the conceptions relating to modern volcanic 

 rocks, as revealed by these new methods, methods which in delicacy, in 

 certainty, and in elegance, are unsurpassed in any other branch of 

 natural science. Not only have they enabled us to verify and control 

 hypotheses, but they have led to the remarkable discoveries to which 

 I am about to refer. 



The eye, assisted even by the most powerful lenses, could recognize 

 in lavas only those minerals which appeared in rather large crystals ; 



* Nature, xxxix. (1889) pp. 271-7. 



