‘ Gsland of Lemnos. 
‘altitude, without refraction. 
==" « ea ee 
213 
more than double the height of the tower 
of Nétre Dame, four times the height of 
the large pyramid ; or three times that 
ef Mount Valerien. Not a mountain 
then, but only a bill, was required for 
displaying the signals at Lilybeum ; if 
we follow the usual distinction of giving 
the name of mountain only to heights 
exceeding 1,000 metres, or 515 thises. 
Another question may here arise, whe- 
ther it were possible to see so far with the 
naked eye? At Lyons they distinctly see 
without glasses Mont-Blanc, distant from 
that city about 18 myriametres, 029 (57 
Jeagues): and from Nice one>may dis- 
cover with the naked eye the mountains 
ef Corsica, which are distant 28 myriame- 
tres (about 57 leagues). The first of 
these distances exceeds a fifth, and the 
second is almost double, the interval be- 
tween Marsalla and Cape Bon. 
There cannot, therefore, any doubtre- 
main respecting the factgivenbyPolyanus, 
By applying the same calculations to 
the signals of Agamemnon, | have proved 
the possibility of them with respect to the 
distances between the different stations ; 
for the greatest of them is half'a myria~ 
metre (a league) less than that from Mar- 
salla to Cape Bon. But are the stations 
of Agamemnon’s beacons likewise suffi- 
ciently high to render the signals visible? 
—Lhave proved this by reference to their 
heights, as taken from the computations 
of navigators. That of Mount Athos is the 
only one I have not obtained in a direct 
manner. Itis not inserted in any geo- 
graphical work ; we find, indeed, a note 
engraved on Arrowsmitl’s map of the 
Envirous of Constantinople, that it is 
equal to 35 feet; butitdoes notsay, whe- 
ther this be the result of trigonometrical 
operations, or merely an estimate. [have 
endeavoured to obtain ‘the height of 
Mount Athos from a passage of Pliny, 
(lib. iv. cap. 12, sec. 23), where that na- 
tural historian informs us, that at the 
solstice Mount Athos projects its shade 
on the market-place of Myrrhina, in the 
I have supposed, that 
‘at the summer solstice, (when, according 
to the position of the two places, the 
shadow of the mountain would extend 
towards Lemnos), the sun, near the time 
of setting, had a sexagesimal degree of 
The re- 
solution of a rectangular triangle, the 
mean side of which 1s the chord of the 
terrestrial arc, which separates Mount 
Athos from Myrrbina, and the small side 
the height of the mountain, gives for the 
latter 1,360 metres, 4 (698 tolses, 2) 
_ Proceedings of Learned Societics. 
7? we ——_— 
ha 
” 
[O& 1; 
which is more than the height of Vesu- 
vius, but less than that of Puy-de-Dome. 
It remains to be proved, that one 
night was suilicient for transmitting intel- 
ligence, by means of these signals, from 
Troy to Argos, The philologists who 
before me have commented on this pas- 
sage, had no facts to adduce in elucidation 
of this question ; but the results of expe- 
riments made with the telegraph has 
enabled me to throw more light on it. 
In the month of August, 1794, the city of 
Condé was retaken by the French, at 
seven o'clock in the morning. The te- 
legraph of Lille, which is distant from 
Condé 4.39 myriametres (nine leagues) 
transmitted the news of the capture to 
Paris, where it arrived between nine and 
ten o'clock. ‘The telegraph of Paris im- 
mediately transmitted to that of Lille 
the decree of the National Assembly, de- 
claring that the army had deserved well 
of their country; and by the same means 
the Assembly received on the same day, 
between seven and eight o’clock in the 
evening, the address of the army, expres- 
sive of their thanks for the honour con- 
ferred on them. Thus in the space of 
fourteen hours intelligence was convey- 
ed through a space of 59 myriametres, 
(or 123 leagues), i. e. a third more than 
the length of the line of beacons estab- 
lished by Agamemnon, - 
Encouraged by this result, I applied 
the same method to the illustration of 
other passages of ancient authors, rela- 
tive to signals, Czsar (BellGall, vii. 
cap. 3), speaking of the Romans who had 
been massacred at Genabuin (Orleans), 
says, “ When any event of importance, 
and which concerns the general interests 
of the nation, happens amongst’ the 
Gauis, they communicate the intelligence 
of it by loud cries across the fields. 
These cries are heard by others, who in 
like manner repeat them to their neigh- 
bours. This was done on the present 
occasion ; for before the end of the first 
watch, the inhabitants of the borders of 
the Averni (Auvergne,) had been made 
acquainted with what had been transact- 
ed at Genabum (Orleans) at sun. rise, 
though the interval be about 160,000 
paces (23 nfyriametres, 555, or 49 leagues 
of 2,500 toises),”” 
In order to ascertain whether what is 
here recorded excceds the bounds of 
possibility, I made some experiments in 
the Place des Invalides ; and I learned 
from the results, that in calm weather, 
or at a distance from hills or hauses 
which cause an echo, or ina plain, we 
cannot 
