324 ABRIDGEMEN TS of 
In order to increafe the furface of the lower part of the 
condu@or, let a hole or. pit, of fuffcient extent, be dug 
as deep as convenient; and into this pit, let there be 
put a quantity of charcoal, round the lower extre- 
mity of the rod. Charcoal  poflefies two properties 
which, ina peculiar manner, fit it for anfwering the pur- 
pofe here in view, (1) It is. a very good conductor of 
electricity, and (2) it will undergo little or no change of 
property by lying ever fo long intheearth. Thus might 
the furface of that part of the conductor, in conta& with 
the earth, be increafed with little trouble or.expence to any: 
extent at pleafure; a circumftance which every one ac- 
quainted with electrical experiments, mult acknowledge 
to be of great importance to the end here propofed. 
Whither the above hints may merit a place among the: 
communications from candidates for the annual premium, 
is humbly {ubmitted | 
By yours, &c. 
PHILO FRANKLIN.- 
N®. XXXVI. 
An eafy and expeditious method of diffipating the noxious. 
Vapour commonly found in Wells and other fubterraneous 
places, by EBENEZER ROBINSON, Of Philadelphia. 
Read (Nov: FT ER various unfuccefsful trials, (a detail 
ad. 2986. of which has been already communicated,) 
I was led to confider, how I could convey a lar.e quantity 
of freth air, from the top to the bottom of the well; fup- 
pofing that the foul would neceflarily give way to the pure 
air.—With this view I procured a pair of {miths we 
xed 
