BY THE PUESIDENT. 163 



in motion, they probably move in a circle, and perpetual circular 

 motion is probably a law of Nature. It is to my mind as difficult 

 to conceive of any body stationary in space as that time should be 

 stationary ; in fact, time is only measured motion. 



My examples last year were taken from healthy Natiare ; I 

 propose this evening to endeavour to show that the same law is 

 to be observed working in diseased Nature. It may seem to some 

 that it is out of place to mention disease in a Natural History 

 Society. I hope a little consideration will show that the subject 

 is not inappropriate, and it may be useful ; for our versatile 

 Premier says: "The health of a people is mostly the foundation 

 upon which all their happiness and all their power as a nation 

 depends." I shall treat the subject as a physicist, not as a 

 physician, and only deal in generalities. 



The study of Natural History, as generally understood, has 

 many charms and many advantages. It promotes health of body 

 and health of mind ; but for my part, I should not devote any 

 time to its pursuit if it were not for its many practical applications 

 — its use in our every-day life. I study, and I advise others to 

 study, what may be called practical Natural History. AVe are 

 travelling through this world for a short time with many fellow- 

 creatures of the animal and vegetable kingdoms, and it contributes 

 not only to our pleasure, but to our advantage, and to our profit, 

 to become acquainted with the habits and instincts and various 

 relations of our fellow-travellers, not only that we may make use 

 of them for our personal pleasure aud benefit, but that we may be 

 useful to them also. I shall not detain you by mentioning the 

 various studies that might be included under practical Natural 

 History ; they may suggest themselves to your minds. I may 

 mention that the diseases which affect the silk-worm, the vine, the 

 hop, and the potato, the no-longer dreaded Colorado beetle, the 

 Epizoa, and the Entozoa, are all a fruitful field for study. With 

 regard to this subject, it has been said (by Andrew "Wilson, in the 

 * Gentleman's Magazine ') : " The field of inquiry seems well nigh 

 boundless ; and it should certainly form one of the most power- 

 ful arguments in favour of the study of natural science, that on 

 the advance of our knowledge of economic botany and zoology 

 the prosperity of our commerce and the conservation of our health 

 may be shown largely to depend." 



Nature may be divided into two classes, healthy and diseased. 

 The same natural laws govern both, and the facts that we observe 

 in the one throw light on the other. I shall not detain you with a 

 definition of disease ; but I may remark that I do not regard it as 



