576 



THE POPULAR SCIENCE MONTHLY. 



structions to forward them to the nearest 

 Swedish consul. The manuscripts have not 

 been fully examined. 



PROF. FRANKLAND says that while the 

 virility of many bacteria can be greatly 

 reduced by successive cultivations, and the 

 poisonous effects of such active bacteria as 

 those of typhoid and cholera can be intensi- 

 fied by passing them repeatedly through the 

 bodies of animals which at first offered 

 great resistance to their pathogenic action, 

 this increase in toxic effect can not be pro- 

 duced by artificial cultivation, and it has not 

 been found possible to convert a harmless 

 organism into a pathogenic one. 



A CURIOUS case of resuscitation of an 

 optical image has been described by Prof. T. 

 "Vignoli from his own experience. After a 

 railway journey in a bright sun and two 

 days' walking in the heat, he looked from 

 the room in which he was engaged in con- 

 versation upon a balcony standing out in the 

 bright sunlight. Early in the morning two 

 days afterward, while lying awake in bed, 

 he saw upon the ceiling an exact reproduc- 

 tion of the balcony, in all its colors and de- 

 tails. The image disappeared on closing the 

 eyes, and reappeared on opening them again. 

 Its appearance was not changed when it 

 was regarded with one eye, looking with 

 either alternately. It was interrupted by 

 putting the finger in front of the eye, and 

 responded in every respect to the usual 

 features of ordinary vision. A cage of birds 

 which hung upon the original balcony ap- 

 peared, swinging as the real cage did. 



WHAT is undoubtedly the first publication 

 of Asa Gray, although it is not included in 

 the published lists of his writings, has been 

 sent to Garden and Forest. It is a cata- 

 logue of the indigenous flowering and filicoid 

 plants growing within twenty miles of Bridge- 

 water, Oneida County, New York. It consists 

 of nine pages, is dated January 1, 1833, or 

 when the author was just in his twenty-fourth 

 year, and is contained in the forty-second an- 

 nual report of the Regents of the University 

 of the State. It is also included in Prof. 

 Britton's List of State and Local Floras of 

 the United States and British America, where 

 it is entered under Onondaga County. 



CONCERNING his experience with horse- 

 shoes of aluminum, M. Japy reports that as 

 that metal is four times lighter than iron a 

 complete outfit of shoes of it will weigh no 

 more than a single iron horseshoe. Horses 

 accustomed to iron shoes when shod with 

 shoes of aluminum imagine themselves bare- 

 footed, and are as careful in planting their 

 steps as if they were unshod. The shoes 

 open out as the hoof expands, and conse- 

 quently never cramp it. An aluminum horse- 

 shoe will last from forty to sixty days, ac- 

 cording to the composition of the alloy and 

 the kind of work done by the horse. M. 



Japy concludes that aluminum can be util- 

 ized in shoes for race and carriage horses, 

 and that it may be of service in the treat- 

 ment of diseases of the hoof. It should, how- 

 ever, be used only by persons experienced hi 

 working the metal. 



AN instrument which he calls a formeno- 

 phone has been invented by a French en- 

 gineer, M. E. Hardy, for detecting the pres- 

 ence and estimating the proportions of gas- 

 eous impurities of an atmosphere by the 

 sound they give in a pipe. It is based upon 

 the principle that air passing through an or- 

 gan pipe gives a definite and constant tone, 

 while if any other gas is mixed with it the 

 tone varies according to the gas and the 

 quantity of it. Two instruments of similar 

 construction are used one arranged so that 

 pure air, the other that the air to be meas- 

 ured shall be made to pass through pipes 

 of identical construction. 



THE importance of taking thorough pre- 

 cautions in the case of animals dying of in- 

 fectious disease is newly illustrated in an ob- 

 servation made by the Russian Diatroptoff. 

 The water of a particular well was supposed 

 to be the cause of an epidemic outbreak of 

 anthrax among certain sheep. Xo contami- 

 nation was found in the water, but the mud 

 at the bottom of the well contained a microbe 

 which produced anthrax on being inoculated 

 into a sheep. The germs are supposed to 

 have percolated through the soil to where 

 they were found. The anthrax among the 

 sheep ceased on the well being closed. 



IN a paper on Grinding and Polishing, 

 Lord Rayleigh, after referring to the accu- 

 racy with which optical surfaces can be 

 worked, said that the operation of grinding 

 did not produce scratches on a glass surface, 

 but that pits were cut into an otherwise plane 

 surface by it. A surface so ground, when 

 used for a lens, gave excellent definition, but 

 great loss of light by irregular reflection. To 

 remove this defect the lens had to be pol- 

 ished, by which operation the pits were 

 gradually removed. He gave reasons for 

 believing that in the process of polishing the 

 glass was worn off molecularly, whereas 

 grinding removes fragments of the glass. He 

 found that in poh'shing a certain thin disk of 

 glass a thickness equal to about six wave- 

 lengths of yellow light was removed. It was 

 easy to remove as small a depth as half a 

 wave-length by means of hydrofluoric acid if 

 proper precautions were taken. 



MOLDS differ from bacteria, according to 

 Prof. Frankland, in their action, and pro- 

 duce an oxidation, or burning up, instead of 

 fermentation. 



A NEW section, that of physiology, has 

 been formed in the British Association. It 

 is the ninth section, and will be designated 

 by the letter I. 



