ASTRONOMICAL AND PHYSICAL OBSERVATORIES. 365 



thread : besides, the difference between the instants noted, or what is 

 termed the " personal equation," of two astronomers, varies more or 

 less according to circumstances, and may increase or diminish with 

 time. The observer's training has a great deal to do with it, Wolf 

 having demonstrated that, by practice, the time lost may be reduced to 

 a minimum, with the employment of a special apparatus. 



An important conclusion follows irresistibly from these experi- 

 ments : it is, that the nerve-fluid is not identical with the electric fluid. 

 Electricity darts through telegraphic wires with inconceivable rapidity, 

 far outspeeding light, and moving 20,000,000 times faster than the 

 nerve-agent. There exists another important difference between these 

 two forces. Any alteration in the structure of the nerves checks the 

 transmission of the nerve-current ; crushing or partial burning is 

 enough to interrupt its passage; once cut, they do not regain their 

 conductive power when the separated ends are brought together again. 

 Metallic wires, on the contrary, conduct electricity in spite of all the 

 injuries that may be inflicted on them. Yet the well-known labors of 

 Prof. Dubois-Reymond clearly prove that electricity plays a part of 

 some kind in nervous phenomena. Electric currents exist naturally in 

 nerves, and these currents are influenced and modified by the action of 

 the nerve-currents. It may be admitted, then, that nervous phenomena 

 are the result of a secondary action of electricity, producing certain 

 changes, chemical or otherwise, in the nerve-substance ; these manifest 

 themselves only after the lapse of a certain time, during which the ac- 

 tion increases in a slow and gradual manner till it becomes sensible, 

 and produces mechanical effects. This side of the question is still en- 

 veloped in profound darkness, and we are driven to more or less plau- 

 sible hypotheses. Still, we can say that a great step has been taken 

 toward the solution of the problem of life: the experiments of which 

 this account is given have thrown light upon its approaches, and placed 

 the question on the ground of exact science. No doubt a long time 

 will pass before the progress of methods of observation shall permit us 

 to make one step nearer to the goal, and nothing authorizes the be- 

 lief that we can ever fully reach it ; but we may take pride in what 

 has already been done, since the exactness of the results gained sur- 

 passes all expectation. Revue des Deux Mondes. 







ASTRONOMICAL AND PHYSICAL OBSERVATORIES. 



IT has been said that " dirt is but matter out of place," and we may 

 likewise take for an axiom that error is lorce misapplied. It 

 cannot be complained that the age in which we live is one which de- 

 mands the most careful economy of our forces of all kinds, nor are we 

 intellectually in the position which geologists are fond of predicting for 



