58 



POPULAR SCIET^OE NEWS 



[April, 1888. 



have been a very strong defence against an 

 armj' equipped onl^- with spears or bows and 

 arrows. Under- such circumstances it would 

 seem as if it could only be taken b}' force of 

 numbers, and these ancient structures have 

 doubtless been the scene of many terrible 

 conflicts. 



RECENT FEATS IN PHOTOGRAPHY. 



The total eclipse of the moon last January 

 suggested to MM. Dumont and Bergeret of 

 Nancy, France, the hapi)_v idea of registering 

 the different phases by means of direct pho- 

 tograph}-. The engraving (Fig. 1) is a copy 

 of the photograph thus obtained. The succes- 

 sive exposures were four seconds in length, 

 separated by intervals of five minutes. The 

 gradual increase of tlie total phase as the 

 image of the moon 

 moved over the 

 plate, is beautifully 

 shown, and those 

 who enjoyed a view 

 of the eclipse can 

 testify as to the ac- 

 curacy of the pho- 

 tograph. 



The first success- 

 ful instantaneous 

 photographs of 

 moving men and 

 animals were, we 

 believe, taken by 

 Mr. Muybridge of 

 San Francisco. 

 The two accom- 

 panying engravings 

 are from photo- 

 graphs of a leaping 



horse and rider, taken by a photographer of 

 Brussels. Tlie position in Fig. 2 is somewhat 

 similar to tlie conventional attitude in which 

 artists are accustomed to paint figures of leap- 

 ing horses, but a glance'at Fig. 3 will show 



graphic plate notes and records almost in- 

 stantaneously. 



Pictures like these, which are taken in an 

 inappreciable fraction of a second, are a strik- 

 ing proof of the advance of the science from 

 the time when Dr. Draper considered it a 

 triumph of art to obtain a dim image of a 

 neighboring chimney upon adaguerrotype plate 

 after an exposure of twenty minutes. 



The engravings illustrating this article are 

 reproduced from La Nature. 



[Special correspondence of the Popular Science J^eios.] 



PARIS LETTER. 



The topic of the day in biological circles is the 

 result of the recent experiments of Professor Brown- 

 Sequard and his assistant Mr. D'Aisonval concern- 

 ing "the toxio_, properties of the air expired by 



»t^tnf)V^Vl^ >> > > > > 



how different the actual position really is. It 

 is evident that no horse could remain in such 

 a position for anj- appreciable length of time ; 

 and as the e3'e requires about a sixteenth of a 

 second to perceive any object, it is not able 

 to note all the different positions taken by 

 the quickly moving horse, which the photo- 



healthy men or animals. The experiment is made 

 in the following manner: An animal or man is 

 made to expire in a tube which leads into a glass 

 reservoir; both are surrounded with cold water and 

 ice, so that the condensation of puhnonary vapors 

 is immediately effected. If the process is continued 

 for some time, a sufficient quantity of water is 

 obtained, which may be used for experiments. 

 Another method consists in filling a lung with 

 water, and then emptying it, and using the water. 

 There seem to be very toxic properties belonging 

 to the liquid so obtained; if it is subciitaneously 

 injected in different animals (dogs, rabbits, etc.), 

 death generally is the consequence at the end of a 

 short period, unless the dose is a weak one. In this 

 last case (dose of four or six grams of watei) there 

 are curious symptoms to be observed, — the pupils 

 dilate, the breath is much slower, the temperature 

 falls (sometimes live Centigrade degrees), and a 

 general paralysis supervenes, especially in the 

 posterior limbs. The next day the heart seems to 

 be affected, and becomes quite rapid. Death is 

 generally, after a few days (sometimes a few hours 

 with high doses), the consequence of the experi- 

 ments. The fact is all the more interesting since 

 it has been recently demonstrated that the air 

 expired, even by persons or animals with tubercu- 

 lous lungs, never contains any bacteria. So bac- 

 teria cannot be the cause of the toxic properties 

 of expired air, inasmuch as the water obtained by 

 either of the methods described is always passed 

 through filters, to prevent the presence of all 

 organic bodies; and it must be concluded that the 

 lungs are the seat of some special secretion (gaseous 



or aeriform, of course), and that the products of 

 this secretion (some leueomaine or other animal 

 alkaloid) are endowed with highly toxic powers. 



Whil« speaking of bacteria and allied subjects, 

 I must say a word of the results of Pasteur's 

 recent experiments upon his proposed method of 

 destroying rabbits in Australia. The facts are 

 well known: The Australian government, much 

 frightened by the considerable damage caused by 

 the wild rabbits in agricultural districts, where 

 they have increased of late in enormous propor- 

 tions, has offered a considerable sum of money to 

 induce researches towards the discovery of some 

 method of destruction of the unfortunate animals. 

 M. Pasteur, on hearing of the matter, remem- 

 bered having observed the destructive effect upon 

 rabbits of one of the numerous bacteria, studied 

 by himself, — the bacteria of fowl-cholera. He 

 accordingly repeated his previous experiments, 



feeding rabbits with 

 grass which had been 

 moistened with fowl- 

 cholera cultures, and 

 saw that the effects 

 were very rapid and 

 fatal. At this time 

 he received a letter 

 from a lady whose 

 name is connected 

 with one of the best 

 brands of champagne, 

 ilme. Pommery of 

 Reims, who informed 

 him, that, if he cared 

 to try an experiment 

 upon a large scale, 

 she could enab|le 

 him to do so. She 

 owned a large park 

 entirely closed with 

 • walls, in which rab- 

 bits had become ex- 

 ceedingly numerous, — too much for her personal 

 comfort, — and she was quite willing to give M. 

 Pasteur a chance. He seized upon it immedi- 

 ately, and sent one of his assistants with fowl- 



Fio. 3. 



cholera culture to Reims. The grass around the 

 rabbits' holes was watered with the culture, and the 

 results were splendid. Rabbits were found dead 

 on the ground and in their holes, in quantities. 

 It seems, then, that M. Pasteur's method is a really 



