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glafs cafe, v»'lie re they may enjoy the fun and have free air 
in mild weather. During the winter feafon thefe plants 
mud be fparingly watered ; for as their (iems are fuccu- 
lent, too much moifture will caufe them to rot. In the 
fummer they (hould be fet abroad in a (bettered fituation, 
and treated in the fame manner as .other plants from the 
fame country. The fourteenth fpecies is annual, and the 
mod beautiful of all the forts. The feeds mud be fown 
every year where they are defigned to remain; and the 
plants require no other culture but to keep them clean 
from weeds, and to thin them where they grow tooclofe. 
In July they flower, and their feeds ripen in five or fix 
weeks after. The feeds of the other forts being fown in 
the fpring, will, thefecond fummer after, produce flowers 
and feeds, after which they feldom continue. They all 
■delight in a rubbifhy gravelly foil, and will grow upon 
the tops of old walls or buildings; where, when once 
they have edabliflied themfelves, they will drop their 
feeds, aiid thereby maintain a fttcceflion of plants without 
any care, and on thefe places they appear very beautiful. 
See Lycopsis, Myosotis, Onosma, and Pulmonaria. 
E'CHIUS, or Eckius (John), a celebrated German 
catholic divine and controverfialid, was born at a village 
in Suabia, in the year 14S6. Having embraced the ec- 
clefiadical life, he became dodtor and profefior of theo¬ 
logy in the univerfity of Ingoldadt. He made himfelf 
famous by his controverfial writings againfi the reform¬ 
ation, and the leading part which he took in the public 
difputes with Luther, Carlodadt, and Melandlhon. He 
was confidered as one of the mod learned and able de¬ 
fenders of the church of Rome, and has had exalted enco¬ 
miums pafled on his fervices by the writers of that com¬ 
munion. He died at Ingoldadt, in 1543, when he'was 
fifty-feven years of age. He was the author of two trea- 
tifes, 1. On the Sacrifice of the Mafs. 2. A Commentary 
on the Prophet Haggai, 8vo. 1638. 3. Homilies, 4 vols, 
Svo. and numerous controverfial pieces againd the pro- 
tedants. 
E'CHO, /i [s%w, Gr. echo, Lat.] Sound reflected or re¬ 
verberated from fome oppofing body, and thereby re¬ 
turned or repeated to the ear : 
Babbling echo mocks the hounds, 
Replying fhrilly to the well-tun’d horns, 
As if a double hunt were heard at once. Shahefpeare. 
To ECHO, v. n. To refound ; to give the repercuffion 
of a voice : 
Through rocks and caves the name of Delia founds ; 
Delia each cave and echoing rock rebounds. Pope , 
To be founded back: 
Hark, how the found didurbs imperious Rome ! 
Shakes her proud hills, and rolls from dome to dome ! 
Her mitr’d princes hear the echoing noife, 
And, Albion, dread thy wrath and awful voice. Blackm. 
To E'CHO, v. a. To fend back a voice; to return what 
has been uttered.—Our feparatills do but echo the fame 
note. Decay of Piety . 
One great death deforms the dreary ground. 
The echo'd woes from diftant rocks refound. Prior. 
The following theory of echoes is given by Dr. Hut¬ 
ton : For an echo to be heard, the ear mud: be in the line 
of reflection; that the perfon who made the found may 
hear the echo, it is neceflary he (hould be in a perpen¬ 
dicular to the place which refletts.it; and, for a multiple 
echo, it is neceflary there be a number of walls and vaults, 
rocks and cavities, either placed behind each other, or 
fronting each other. Thofe murmurs in the air, that are 
occafioned by the difeharge of great guns, &c. are a kind 
of indefinite echoes, and are produced from the vaporous 
particles fufpended in the atmofphere, which refill the 
undulations of found, and reverberate them to the ear. 
There can be no echo, unlefs the direct and reflex founds 
toliow one another at a fufficient diftance of time ; for, 
Vol. VI. No. 345. 
037 
if the reflex found arrive at the ear before the impreflion 
of the direct found ceales, the found will not be doubled, 
but only rendered more imenfe. Now, if we allow that 
nine or ten fyllables can be pronounced in a fecond, in 
order to preferve the founds articulate and diftindt, there 
(hould be about the ninth part of a fecond between the 
times of their appulfe to the ear; or, as found flies about 
1142 feet in a fecond, the faid difference (hould be one- 
ninth of 1142, or 127 feet; and therefore every fyllable 
will be reflected to the ear at the diftance of about feventy 
feet from the reflecting body; but as, in the ordinary 
way of fpeaking, three or four fyllables only are uttered 
in a fecond, the fpeaker, that he may have the echo re¬ 
turned as foon as they are exprefled, (hould (land about 
500 feet from the reflecting body; and fo in proportion 
for any other number of fyllables. Merfenne allows for 
a mo.nofyllable the diftance of fixty-nine feet; Morton, 
ninety feet; for a diffyllable 105 feet, a trifyliable 160 
feet, a tetrasyllable 182 feet, and a pentafyllable 204 feet. 
From what has been faid, it follows that echoes may 
be applied for meafuring inaccefiible diftances. Thus, 
Mr. Derham, (landing upon the banks of the Thames, 
oppofite to Woolwich, obferved that the echo of a Angle 
found was reflected back from the houfes in three feconds; 
confequently the fum of the direCt and reflex rays mu(l 
have been 1142 x 3 = 3426 feet, and the half of it, 1713 
feet, the breadth of the river in that place. It alfo fol¬ 
lows that the echoing body being removed farther off, it 
reflects more of the found than When nearer; which is 
the reafon why fome echoes repeat but one fyllable, or 
one word, and fome many. Of thefe, fome are tonical, 
which only.return a voice when modulated into fome par¬ 
ticular mufical tone ; and others polyfyllabical. That 
fine echo in Woodftock park, Dr. Plot allures 11s, in the 
day-time will return very diltihCtly feventeen fyllables, 
and in the night twenty. See Nat. Hijl. Oxf. p. 7. 
Echoing bodies may be fo contrived, and placed, as 
that refleCting the found from one to the other, a mul¬ 
tiple echo, or many echoes, (hall arife. At Rofneath, 
near Glafgow, in Scotland, there is an echo that repeats 
a tune played with a trumpet three times completely and 
diflinCtly. At the Rpulchre of Metella, wife of Craffus, 
there was an echo, which repeated what a man faid, five 
times. Authors mention a tower at Cyzicus, where the 
echo repeated (even times. There is an echo at Bruffels, 
that anfwers fifteen times. One of the fined: echoes we 
read of, is that mentioned by Barthius, in his notes on 
Statius’s Thebais, lib. vi. ver. 30. which repeated the 
words a man uttered feventeen times. This was on the 
banks of the Naha, between Coblentz and Bingen. In 
common echoes, the repetition is not heard till fome time 
after hearing the words fpoken, or the notes fung; but, 
in this cafe, the perfon who fpeaks, or fings, is (carcely 
heard at all; but the repetition very clearly, and always 
in furprifing varieties ; the echo feeming fometirnes to 
approach nearer, and fometirnes farther oft’; fometirnes 
the voice is heard very diftinCily, and fometirnes hardly 
at all: one perfon hears only one voice, and another feve- 
ral; one hears the echo on the right; the other on the 
left, &c. 
Addifon, and other travellers in Italy, mention an echo 
at Simonetta palace, near Milan, dill more extraordinary, 
returning the found of a piftol fifty-fix times. The echo 
is heard behind the houfe, which lias two wings ; the 
piflol is difeharged from a window in one of thefe wings, 
the found is returned from a dead wall in the other wing, 
and heard from a window in the back-front. Addifcn's 
Travels, p. 32. Mijfon. Voyag. d’ltal. tom. ii. p. 196. Phi. 
lof. TranJ. N b 48o. p. 220.—Farther, a multiple echo may 
be made, by fo placing the echoing bodies, at unequal 
difiances, as that they may reflect all one way, and not 
one on the other; by which means, a manifold fucceflive 
found will be heard ; one clap of the hands like many ; 
one ha like a laughter; one Angle word like many of the 
fame tone and accent; and fo one mufical inftrument 
3 P like 
