8 TRANS. OF THE ACAD. OF SCIENCE. 



at Washington, the other for myself. I received mine in the 

 summer of 1860, but parts of it were injured by transporta- 

 tion, and a new glass thread had to be inserted (a very deli- 

 cate operation), so that I could not begin using it before 

 July. The instrument worked very well, but it was several 

 months, before I thoroughly understood all its delicate mo- 

 tions and occasional whims. The management of the collect- 

 ing apparatus gave me also some trouble, because my house, 

 though a corner house, with a free circulation of air, did not 

 allow of conveniently raising the ball above the roof in the 

 manner described by Prof. Dellmann. But by using an attic 

 of my house, I arranged it so that, with a pole about eight 

 feet long, the collecting apparatus could be easily thrust out 

 of the window to a height, in which the air has free access 

 from all sides ; then, after having touched the stem of the 

 ball with the half-moon shaped metal, I let down the poie 

 as last as possible and approach the charged ball, at once, to 

 the measuring instrument, which stands close by the win- 

 dow. The time from the charging of the ball to its connec- 

 tion with the measuring instrument is, on an average, not 

 more than twelve seconds, which is of some importance, 

 since any delay occasions a trifling loss of electricity. 



I found also some difficulty in keeping the collecting appa- 

 ratus perfectly isolated. Prof. Dellmann has for this purpose 

 surrounded the lower part of the stem of the ball, where it 

 is inserted in the metallic box, with two thick rings of shel- 

 lac and a piece of leather. But during our summer heat 

 these rings frequently cracked and broke and needed con- 

 stant mending. I therefore inserted in the bottom of the 

 metallic box a small, well-fitting porcelain pot, filled with 

 melted shellac, and in its midst the metallic stem. To the 

 upper part of the metallic box, I fitted a thick glass, such as 

 is used for lightning rods, filled its centre with shellac, and 

 run the stem through it. The stem was thus doubly isolated 

 (by shellac and glass or porcelain) and rendered also less 

 liable to injury. 



After having thus completed my preparations, and while 

 I was gradually gaining more experience, in the use of the 

 instrument, I happened to break the tender glass thread by 

 some mismanagement. This occasioned ngain some inter- 

 ruption in my observations; but, during the fall and winter 

 of 1860, they were continued without any further accident. 

 During the entire year of 1861, I made the observations as 

 regularly as possible, about six times daily and sometimes 

 oftener. I noted, at the same time, all the other meteorolo- 

 gical phenomena, to ascertain their direct or indirect connec- 

 tion with atmospheric electricity. This meterological jour- 

 nal of 1861 is herewith offered to the public. Embracing, 

 as it does, between two and three thousand observations, 



