902 Transactions of the American Institute. 



were seen. He next used a glass tube of the same size, but exhausted 

 of air, when no electric liglit could be observed. The doctor, how- 

 ever, remarked that he could see a faint spark passing from the 

 points, which he attributed to the glass tube not being thoroughly 

 exhausted of air. In 1863, a dark spot was observed on the sun; this 

 large dark mass must have moved over a space of some twenty thou- 

 sand miles. At the instant when the darkness reached the earth, the 

 magnetic needle in the observatories were disturbed, showing that 

 when the shadow reached our planet, there was a " sunquake " which 

 . affected the needle. In making some experiments with the barometer 

 he observed that by tilting it to one side so as to cause the mercury 

 to run up and down the tube, flashes of light could be seen in the 

 dark, caused by the friction of the mercury on the glass. There is also 

 a vapor of mercury coming from the mercury, even in the open air. 



The latest theory in regard to the magnetic needle is, that the cur- 

 rents from east to west are caused by the alternate heating of the 

 earth by the sun during the day, and cooling again at night, and in 

 that way influences the currents. 



Dr. D. D. Parmelee said that, in order to get the electric light, it 

 is necessary that a break in the current be made. He could not con- 

 ceive how this could be made in the barometer. Is not the light seen 

 in the tube the result of phosphorescence ? A Leyden jar in contact 

 witli a receiver will not give off sparks, if they are not some distance 

 apart from each other. He could not understand how Dr. Y. inferred 

 this to be electricity. 



Dr. Yanderweyde replied that, when the mercury leaves the glass 

 at the top of the barometer tube, it generates electricity, and the 

 luminosity is due to the spark passing through the mercurial vapor. 

 Phosphorescence and electricity are the same. The animals of the 

 ocean that produce phosphorescence have some electrical apparatus 

 that enables them to produce sparks. Many cases of phosphorescence 

 are entirely due to electricity. Some twenty years ago he made 

 experiments on the pliosphorescence of sea water in Holland. The 

 sea water runs in tlie canals of the city. He found that the water, 

 when placed in a glass vessel, after resting a while, collected some- 

 thing on the top about half an inch thick, wliicli he found to be 

 monads, that gave a light when suddenly disturbed. There was no 

 di)ubt but that the animalcules were the cause of the disturbance. He 

 placed some slimy matter under the microscope, and found it filled 

 with animalcules. Phosphorescence is of electric origin. 



