Bache.] ^*^ [April 20, 



towards the earth or among themselves. He, from the first, recog- 

 nizes the fact that the smaller the particles are, the more vivid is their 

 movement. He recognizes another, that, although many large par- 

 ticles do not, as masses, move at all, yet the larger masses are all 

 alive, as it were, with smaller ones, seen clearly around their periph- 

 ery, on the silhouette of which they are seen plying like banks of 

 oars in an ancient trireme. He is struck with and convinced of 

 still another thing, that whereas one might expect to find that all 

 particles would manifest an attraction for each other through gravi- 

 tation, and that the larger and largest, but all in proportion to their 

 relative size, would attract and absorb the relatively smaller and 

 smallest ones, nothing of the kind occurs, but the smaller, down to the 

 smallest, go their own way, sometimes even touching the largest 

 and bounding off and away as if they do not, as indeed they do not 

 visibly, submit to the force of gravitation. Of course they cannot 

 escape the influence of gravitation, whether terrestrial or among 

 themselves, but the effect of gravitation upon them is masked, in 

 what manner will appear later. 



It seemed to me that magnetic earth-waves might affect particles 

 in such delicate suspension as those of which we are speaking, some 

 of which are no greater in diameter than 1-100,000 of an inch, seen 

 under various powers capable of magnifying from 650 to 1300 

 diameters. Accordingly, I have placed the particular fluid under 

 examination in the lines of force of a permanent magnet, with the 

 magnet on one side and the keeper on the other of the drop of fluid. 

 Concentrating the gaze on individual particles, to observe if their 

 movement were modified, and then on others in succession, and 

 often repeating the experiment, nothing could be observed other 

 than the movements existing before the magnet had been brought 

 into requisition. The only kind of particles susceptible to the influ- 

 ence of tlie magnet were those of precipitated iron, but iron is 

 always obedient to the magnet. 



Heat I applied in various ways, either irregularly or in an en- 

 deavor to distribute it as equably as possible on the glass slide on 

 which the particular experiment was made. Mere currents are set 

 up during the adjustment of temperature from radiation. At the 

 same time one can observe and differentiate tlie motions due lo the 

 brownian movements, the motions along currents, and also the 

 motions from terrestrial gravity, if any, exhibited by particles, if 



