562 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



that, although a very large proportion of small-pox cases had 

 previously undergone vaccination (from seventy-three to sev- 

 enty-nine per cent.), it was manifest that the operation had 

 been imperfectly performed, or had been weakened by the 

 lapse of time. But, even with these disadvantages, the mor- 

 tality among those who had been vaccinated was remarkably 

 small in comparison with that of the unvaccinated. While 

 the general mortality was at the rate of nineteen, per cent, of 

 all attacked with the disease, it was only ten per cent, among 

 the vaccinated, and as high as forty-five per cent, among the 

 unvaccinated. 



The general conclusion reached by Dr. Letheby in his in- 

 quiries was that vaccination, when properly performed, is 

 protective during the growth of the body, and that revac- 

 cination is necessary at the age of fifteen or thereabouts, to 

 protect the system during the remainder of life. 20 A^ June 

 1,1872,635." 



CHOLERA. DISTRICTS. 



An abstract of a very remarkable paper, by Mr. Jenkins, 

 upon cholera, originally presented to the Imperial Academy 

 of Sciences of Russia, is given in a recent number of Nature. 

 In this the author takes the ground that instead of one home 

 or nidus of cholera existing in the delta of the Ganges, there 

 are seven, all situated on or near the Tropic of Cancer, and 

 equally distant from each other, the most important of which 

 is that at the mouth of the Ganges, while the others are to 

 the east of China, to the north of Mecca, on the west coast of 

 Africa, to the north of the "West India Islands, to the west of 

 Lower California, and among the Sandwich Islands; and the 

 author maintains that the recorded appearances of cholera 

 over the globe may be satisfactorily explained by supposing 

 seven atmospheric streams, each 1400 miles in breadth, to pro- 

 ceed from these foci in a northwesterly direction, nearly all 

 of these streams having been in activity at some periods, as 

 during the cholera seasons of 1833, 1850, and 1866. 



The author cites the history of past cholera epidemics to 

 prove the accuracy of his observations, and points out a re- 

 markable law that in 1818 cholera advanced simultaneously 

 in two directions, northwest and southwest, in such a manner 

 that all the places attacked at given times by its northwest 



