'254 PERSONAL PREPARATION FOR RESEARCH. 



He weighed the earth he analysed the air, he discovered 

 the compound nature of skater, he noted with numerical 

 precision the obscure actions of the ancient element, fire. 

 Each, like some visitor to a strange land, was compelled 

 to submit to a scrutiny, in which not only its general 

 features were noticed, but everything pertaining to it to 

 which a quantitative value could be attached was set down 

 in figures before it went forth to the scientific world with 

 its passport signed and sealed. The half-mythical calendar 

 of the Hindoos was submitted to the same ordeal, and 

 made to yield consistent numerical results. The electricity 

 of the torpedo, freezing of mercury, the appearance of an 

 aurora borealis, the hardness of London pump-water, the 

 properties of carbonic acid and of hydrogen, and much 

 else, were equally subjected to a canon which knew of no 

 limitations, and required that every phenomenon and 

 physical force should be held to be governed by law, and 

 admit of expression in mathematical or arithmetical 

 symbols. It seems, indeed, to have been impossible for 

 Cavendish to investigate any question otherwise than 

 quantitatively. If he is making hydrogen, he tells us how 

 much zinc, or iron, or tin he took, and what quantity of 

 gas its solution in sulphuric or muriatic acid yielded, 

 although he had no apparent purpose to serve in measuring 

 the volumes of elastic fluid produced. If he plunges a 

 candle into a mixture of nitrogen and air, or carbonic acid 

 and air, he counts carefully the number of seconds during 

 which it burns, and with unwearied patience varies the 

 proportion of the gases. If he is preparing oxygen, he 

 records in his note-book the weight of mercury he took, 

 the quantity of nitric acid in which he dissolved it, and 

 the amount of gas which the resultant oxide of mercury 

 yielded, although he need have attended to nothing except 



