Electricity—Herba Hispania—New variety of Grape. 
113 
minated by a single fine point, which will be 
amply sufficient. An objection has been made 
with some appearance of plausibility, to a num¬ 
ber of points, lest they should produce an ex¬ 
plosion of electric fluid, when once brought 
within the sphere of their attraction. Various 
metals, such as steel, platina, copper, &c, are 
used for constructing these points, but perhaps 
none are more effectual than soft iron, which 
may be coated with gold leaf or not, as fancy 
may dictate. The coating is not an essential 
requisite, as experiment proves satisfactorily 
that oxidation does not impair the attracting 
property materially. 
The conductor should be elevated according 
to the following principle, viz, that a conductor 
will effectually protect an area of four times 
the diameter that it extends, above any other 
point of attraction. For example. Suppose the 
extreme point of the rod to be ten feet above 
the chimney tops, it would secure a building 
forty feet square. 
A matter of much importance is a proper 
method of attaching conductors to the buildings, 
which may be accomplished in the following 
manner. Take a sufficient number of pieces of 
well seasoned wood of the following dimen¬ 
sions ; fifteen inches long, four inches wide, 
and two inches thick, with a hole through one 
end for the transmission of the rod. These 
should be well boiled in linseed oil, thoroughly 
baked in an oven, and covered with several 
coats of copal varnish, which will render them 
perfect nonconductors. They may be secured 
to the building, by removing a portion of a 
brick and driving them into the wall. Large 
buildings should have a conductor erected at 
each extremity. 
Conductors should not be-painted or varnish¬ 
ed, and to make “assurance doubly sure,” may 
be surrounded with pieces of glass, where they 
pass through the supports. Yours, &c. 
Andrew Campbell, M. D. 
The suggestions of our esteemed correspondent are 
valuable, especially at this season, when thunder 
showers are frequent, and the humid gases from the 
newly secured crops, renders barns peculiarly liable 
to injury. He has well stated the important influence 
of Copal Varnish as a non-conductor, as the Shellac 
which is a principal ingredient of it, is the first in the 
list of non-conductors. Coating the electral points 
with gold is preferable to the naked iron, for not only 
is it a better conductor than iron, but in addition it is 
never subject to oxidation. Recent experiments show 
that electricity is conveyed in proportion to the ex¬ 
tent of surface of the conducting agent, and conse¬ 
quently a number of wires slightly twisted or con¬ 
fined together, afford a more extensive escape for the 
fluid than a single rod. We subjoin a list of the best 
conductors in the order of their respective conducting 
powers : 1 copper, 2 silver, 3 gold, 4 iron, 5 tin, 6 lead” 
7 zinc, 8 platina, 9 charcoal, 10 plumbago (black 
lead), 11 strong acids, 12 soot and lamp-black, 13 
metallic ores, 14 metallic oxides, 15 diluted acids’ 16 
| saline solutions, 17 animal fluids, 18 sea water, 19 
water, 20 ice above 0°, 21 living vegetables, 22 liv¬ 
ing animals, 23 flame, 24 smoke, 25 vapor and humid 
gases, 26 salts, 27 rarefied air, 28 dry earths, 26 mas¬ 
sive minerals. 
The non-conductors in their order are: 1 shellac, 2 
amber, 3 resins, 4 sulphur, 5 wax, 6 asphaltum, 7 
glass and all vitrified bodies, including diamond 
and crystalized transparent minerals, 8 raw silk, 9 9 
bleached silk, 10 dyed silk, 11 wool, hair and feath¬ 
ers, 12 dry gases, 13 dry paper, parchment and 
leather, 13 baked wood and dried vegetables, 15 por¬ 
celain, 16 marble, 17 massive minerals not metallic, 
18 camphor, 19 india rubber, 20 dry chalk and lime, 
21 phosphorus, 22 ice below 0°, 23 oils, the densest 
being the best, 24 dry metallic oxides. En 
For the American Agriculturist, 
New Orleans, May 8th, 1842. 
Gentlemen :—In answer to your inquiries 
concerning the Herba Hispania, the grass of 
Cuba and the grape which I have growing on 
my estate, I will as a memorandum only, give 
you a hasty sketch. 
The Herba Hispania is an Italian grass. 
Its value in a soft, sandy soil, I learn from Dr. 
Cartwright of Natchez, is worth one ton per 
month per acre during the growing months, 
and he is of opinion in our latitude its vegeta¬ 
tion would never cease. 
The grass of Cuba which I have growing 
on the sea shore, my daughter brought from 
Cuba adhering to the root of a Banana plant. 
It has spread over a large surface, and by pull¬ 
ing off the tops or leaves of the grass, and set¬ 
ting it in the earth or sand, it has spread over a 
considerable surface of the white sand of the sea 
shore. It delights in a dry arid sandy land (if 
I may be allowed to call such, land,) and grows 
with great rapidity. The more firmly pressed 
the more rapid the extension. The sward soon 
becomes about 3 inches high, and as thick as 
the growth of wool, and if a dime is dropped in 
it—it is very doubtful if it may be found again, 
as my own losses fully prove. The Plaster of 
Paris seems to have a very happy influence 
upon it, and I should suppose that the lands of 
New Jersey would with this grass make very 
fine sheep walks. 
The grape I obtained from the vicinity of the 
Fort, built by the French, who came to the 
sands of Biloxi some 120 years ago, when 
invited by the Mississippi scheme got up by 
Law, the great financier and humbugger of Pa¬ 
ris. I have no doubt, it is the grape from 
which that rich Burgundy was made in days 
bygone, and of which so much has been writ¬ 
ten. The vine has somewhat of a rough bark, 
is of very rapid growth, the most prolific 
bearer that I have ever seen, and of the largest 
branches. The grape itself is smaller than the 
Madeira, perhaps not more than half the size, 
as closely jutted together as a painting, and 
