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has found that by cultivating and so weakening the virus or 

 poison of this disease he can vaccinate dogs or other animals, and 

 so protect them from all danger of hydrophobia. Thus out of 38 

 dogs, half of which were vaccinated and the other half not, that 

 were bitten by 19 mad dogs, the unprotected animals all died of 

 hydrophobia while the vaccinated speedly recovered. Whether 

 we should any of us personally care to be so vaccinated on the 

 chance of being some day bitten by a mad dog is a moot question, 

 but all dogs exposed to this danger should be at any rate so pro- 

 tected. When we think not only of the thousands of lives that 

 have been saved and the myriads which may be, but the vast field 

 of speculation and enquiry opened up to the Scientist and Physician 

 by the patient labour of one man, we cannot fail to be struck with 

 the advantage of special study. This is a question which interests 

 not only doctors but the world at large, for if animals can be pro- 

 tected by vaccination from Splenic fever, Fowl Cholera, and Eabies, 

 may not mankind look forward to a time when they them- 

 selves may be made secure by similar means from all 

 diseases, such as Diphtheria, Scarlet Fever, Croup, Cholera, 

 Consumption, &o., which arise from germs ? This then is one 

 of the great problems of the day, and it seems in a fair way 

 of being solved. But there is another problem which will also have to 

 be solved, if not by this, certainly by the next generation, and 

 that is the conservation of energy, the economy and utilisation of 

 the enormous stores of now wasted power. For generations past 

 we have been so in the habit of relying on the power generated by 

 the combustion of coal, that we cannot, apparently, bring our 

 miuds to the contemplation of what is to be done when our coal 

 measures are exhausted, which I need not say must happen sooner 

 or later. Already we dig out from our English mines daily a mass 

 of coal which if piled up would make a column 50ft. in diameter 

 and 7,000 ft. high. I need not tell the merest child that this 

 quantity cannot be abstracted each day without causing, at no very 

 distant date, a serious diminution, and finally, an exhaustion of our 

 stores, however large. What then are we to do when our stock is 

 expended. I need remind no member of this society that heat, 

 light, motion, and electricity, are all forms of one and the same- 

 force or energy, and tliat each is convertible into the other. Thus 

 motion may bo made to become heat, as we know from the heating 

 of rapidly revolving axles, or when a cannon ball strikes an iron 

 target jn-oducing heat, with or without a flash of light. A revolving 

 electro-dynamo machine generates electricity, which may again be 

 made to resolve itself into heat, motion, or light, and so on, in a 

 never-ending cycle. But there must be always some form or other 

 of force to start with. Ex nihilo nihil fit. Now it must have struck 



