522 



MICROSCOPY. 



MIGNONETTE CASE, THE. 



" magic-lantern," with broad-wicked lamp and 

 special condensers, or a special construction 

 like Carbutt's " dry-plate lantern," is often con- 

 veniently substituted for the illuminating por- 

 tion of the apparatus ; and a similar adaptation 

 might be made, after suitable changes, of some 

 of the illuminators made for medical and sur- 

 gical use as the laryngoscope, for instance. 



In micrometry a standard has been adopted 

 as a basis of appeal from the discrepancies 

 among the commercial scales formerly avail- 

 able, some of which varied among themselves 

 as much as three or more per cent, of their 

 length. In 1879 a " National Committee " of 

 sixteen members, representing that number of 

 American microscopical societies, was organ- 

 ized through the efforts of the Troy (N. Y.) 

 Scientific Association. President F. A. P. Bar- 

 nard, of Columbia College, N. Y., was made 

 chairman of the committee, and the writer 

 secretary. The committee easily and unani- 

 mously agreed to accept a metric standard, and 

 to adopt the micron (p = O'OOl mm.) as the 

 micrometric unit; also to secure a standard 

 plate, of carefully verified value, representing 

 one cm. subdivided to ten p. On the motion 

 of the committee, the American Society of 

 Microscopists, at its Buffalo meeting in 1879, 

 rescinded the action of the Microscopical Con- 

 gress which the previous year had without due 

 consideration selected the one-hundredth mm. 

 as the micrometric unit. In 1882 a scale an- 

 swering the requirements of the committee, and 

 designated as "Centimetre Scale A, 1882," was 

 prepared for their use upon a platin-iridium bar 

 made by Matthey, and containing 20 per cent, 

 of iridium, by the United States Bureau of 

 Weights and Measures. The limits of the cm. 

 and of its subdivisions were indicated by triple 

 sets of lines, ruled with great distinctness and 

 regularity. The relation of its total length to 

 the standard metre, and the ratio of its subdi- 

 visions, was carefully determined for the bureau 

 by Prof. C. S. Pierce, and remeasured for the 

 committee by one of its members, Prof. Will- 

 iam A. Rogers. Prof. Rogers's elaborate study 

 of the plate led to the conclusion that, assum- 

 ing 0'2 ft to be the limit of precision attainable 

 with certainty in micrometry, the middle de- 

 fining lines of this standard require no cor- 

 rections at 62 Fahr. It was then accepted 

 by the committee, and was adopted as its 

 standard by the American Society of Micros- 

 copists at the Chicago meeting in 1883. The 

 best one of three copies on glass, designed as 

 working-copies for the testing and correction 

 of common micrometers, which were prepared 

 by Mr. Fasoldt to the order of the society in 

 1884, proved to be about 4 p too long. Though 

 the ruling and spacing are otherwise excellent 

 and the error minute in the small subdivisions 

 ordinarily measured, moro accurate copies will 

 doubtless be soon secured (" Proc. Am. S. M.," 

 1879, p. 28; 1883, pp. 178-200; 1884, p. 220). 

 The report of the comparisons of this copy with 

 the original centimetre scale A by Profs. W. A. 



Rogers and W. A. Anthony, -of Ithaca, N. Y., 

 shows an average deviation of only 0*10 /z, Prof. 

 Rogers reporting the scale F to be 4-1 p. too 

 long, according to the mean of his measurements, 

 while Prof. Anthony, working independently, 

 reports it 4'2 /z too long. This is important, as 

 indicating that so small an average deviation 

 as 0*10 /* is attainable with present means of 

 measurement. 



Bibliography. Data pertaining to this subject 

 are scattered throughout nearly all the micro- 

 scopical books and journals of recent years. 

 References are given in the article only when 

 of practical importance ; and for the same 

 reason reviews or reprints most accessible to 

 American readers are usually specified, instead 

 of the original sources from which the data are 

 taken. The following titles which occur fre- 

 quently are designated by initials or other 

 obvious contractions: Carpenter, William B., 

 " The Microscope," sixth edition, London, 1881 ; 

 Behrens, J. W., "The Microscope in Botani- 

 cal Research," American edition, Boston, 1885 ; 

 "Proceedings of the American Society of Mi- 

 croscopists," yearly; "Journal of the Royal 

 Microscopical Society," bimonthly, London; 

 " American Monthly Microscopical Journal," 

 monthly, Washington, D. 0. 



MIGNONETTE CASE, THE. What has been 

 generally called " the Mignonette case " came 

 up in the English courts near the close of the 

 year, and attracted unusual attention, both in 

 Great Britain and the United States, as one 

 unprecedented in the annals of criminal juris- 

 prudence. It raised the question whether 

 killing a human being in case of necessity, to 

 get nourishment to sustain life, is murder. 

 This question had never been decided by any 

 English or American tribunal. Hence, there 

 was no precedent or authority to guide the 

 court in deciding it. 



A small yacht, the Mignonette, left South- 

 ampton for Sydney, Australia, on May 19, 

 1884. The crew consisted of Thomas Dudley, 



captain; Edward Stephens, mate; Brooks, 



seaman ; and Richard Parker, a boy seventeen 

 years of age. These four comprised all on 

 board. The yacht touched at Madeira, crossed 

 the equator, and on July 5, when about 1,600 

 miles from the Cape of Good Hope, was 

 wrecked and went down in a storm. Those 

 on board sought refuge in a boat. The only 

 nourishment they were able to secure from 

 the yacht was two one-pound cans of turnips. 

 They had no other food and no water in the 

 boat. On the fourth day they caught a small 

 turtle. On the twelfth day this and the tur- 

 nips had been consumed, and for the next 

 eight days the men had nothing to eat, and 

 no fresh water to drink except a little rain 

 they had caught in their oil-skin capes. On 

 the eighteenth day, when they had been seven 

 days without food and five without water, the 

 three men began to consider what should b<> 

 done to prolong their lives in case no succor 

 should come. Dudley and Stephens suggested 



