504 PROCEEDINGS OF SECTION H. 



concerning the fitness of this place — opening as it does into the 

 great Pacific and i-eceiving contributions from many lands was 

 correct and manifest to all. Your University will make good use 

 of this wealth of material, will investigate and demonstrate the 

 science pertaining thereto. The Australian Museuni here shows a 

 marvellous collection of natural history which will increase as years 

 go on, and Sydney as a teaching school of science will be unrivalled. 

 With a climate more favourable to health than any European 

 centre can boast, with a cheap, abundant, and varied food supply ; 

 with unlimited fields of recreation by sea and land ; with the 

 English language everywhere ready to comprehend all the require- 

 ments necessaiy for his comfort, the student of medicine and 

 natural science will find here a held for the development of his 

 health and faculties unsurpassed in the world. And to conclude, 

 it is to be hoped that this Association will be of great use in com- 

 bining the wealth of your rich men and the energy and foresight 

 of your philosophers, patriots, and men of taste, so as to produce 

 that high education so necessary for the Advancement of Science 

 in this great and glorious country. 



The following papers were read : — 



1.— ON THE CLASSIFICATION OF PERSONS WHO 

 HAVE BEEN EXPOSED TO THE INFECTION OF 

 SMALLPOX SO AS TO SHOW THE RELATION 

 BETWEEN THE INCIDENCE OF THE DISEASE 

 AND DIFFERENT DEGREES OF PROTECTION BY 

 VACCINATION, OR BY A FORMER ATTACK.* 



By J. AsHBURTON Thompson, M.D. Brux., Dipl. Public Health, 

 Camb., Chief Medical Inspector of the Board of Health, and 

 Deputy Medical Adviser to the Government of N. S. Wales. 



Vaccination is a branch of the science of disease-prevention with 

 which all especially interested in that are perfectly familiar. It 

 seems best, therefore, that I should state a series of brief proposi- 

 tions to which explanatory notes are appended. 



PROPOSITION I. 



The principle of classification is to decide all the cases in which 

 any of the necessary data are defective or wanting, so that they 

 weigh against the protective power of vaccination. 



* This paper was written at the wish of the late Sir William Smart, K.C.B., M.D., 

 R.N., for presentation to the Epidemiological Society of London; but that efentleman 

 having: died, to the loss of epidemiological science, soon after his request was communicated, 

 I feel I cannot do better than present it to this Association. 



