72 The Soientijic Year. [Jan. 



also be used. Pictures by these processes possess more sharpness, 

 and are capable of giving more microscopic detail, than ordinary- 

 wet collodion; moreover, the plates may be prepared the night 

 before and developed alter the ecKpse is over, thus leaving the 

 operator's whole attention free to devote to the exposure of as 

 many plates as possible. 



Secondly, some telescopes should have a system of lenses beyond 

 the principal focus of the object-glass, so as to project a magnified 

 image of the phenomena on to the sensitive plate. The necessary 

 amphfication to four or five inches will be far more accurately 

 done when effected in this manner at one operation than when the 

 small negatives are copied afterwards in the enlarging camera, 

 which will magnify all the defects as well as that which is wished 

 to be recorded. 



Thirdly, the most experienced photographer who can be ob- 

 tained should have charge of the photographic operations. It is 

 a mistake to suppose that astronomers, physicists, and photogra- 

 phers can be manufactured for the occasion. To look at the 

 records of the English expeditions, it would appear as if the 

 highest scientific talent possessed by the country were an exclu- 

 sive attribute of our army and navy. Amongst so many captains 

 and lieutenants it is a rehef to find a plain Mr. The French and 

 German expeditions were managed differently — and contrast their 

 results with ours ! 



VII. THE SCIENTIFIC YEAE. 



If we examine with thoughtful attention the progress of human 

 knowledge, as it is preserved to us in the history of civilization, or 

 in the records of the victories achieved by mind over matter, we 

 cannot fail to observe that it has ever been by slow, and often 

 intermittent steps. The energies of the individual mind, even in 

 the most healthful state, cannot be maintained continuously at the 

 same elevation ; the powers of thought cannot be kept long at the 

 same state of tension. There must be a lowering down, there must 

 be a relaxation. As it is with the powers of the individual, so is it 

 with the aggregated forces of the mind of mankind. The law of 

 undulations, which is so beautifully manifested in all its subtleties 

 of motion, in the phenomena of light, and the other physical powers 

 in motion, is shadowed forth in the movements of iutelloctual 

 power with so defined an outline, that we cannot but regard it as a 

 truth, obscure at present through the many diliicultics by which all 

 psychological phenomena are surrounded, through the imperfections 

 of our senses, and through the almost entiic absence amongst men, 



