422 
duced thereon, exceed all others in theix 
beauty, excellence, and fize. In England, 
Jand. is often pared and burnt, the afhes 
being afterwards fpread as manure; but 
as falt is one great principle of vegeta- 
tion, the afhes from the fea-weed. muf 
obtain a decided preference over all other; 
and in lands newly enclofed from the fea, 
. where the occupiers have fo good an op- 
portunity of collecting fea-weed, it would 
doubtlels be worth their attention to make 
the trial both ef the weed in its natural 
ftate, and alfo of its afhes, to promote ve- 
getation, on which land it proceeds but 
flowly. A, celebrated traveller* has’ re- 
marked that a tract of land belonging 
tothe crown of Denmark, confifting of a 
Grifting fand, on which nothing would 
vegetate, and which injured the neigh- 
bouring lands, was brought to produce a 
_confiderable quantity of good hay, by be- 
ing covered with tea-weed collected from 
the fhore, and which was prevented from 
being blown away by being pinned down 
with twigs of the fr tree. It is faid that 
the ifland of Alderney is one continued 
bed of fand ; fome perion may perhaps be 
able to afeertain whether the ufe of fea- 
weed in any way contributed either to 
form or improve the valuable herbage on 
that ifland. 
In the proceedings of the National In- 
ftitute, mention is made of a fhrub called 
the fea-rufh, ajcnc, or jone marin, the 
Ulex Europeus ot Linneus, If any of 
your corre{fpondents can afcertain whether 
it will grow on fea-walls raifed for keep- 
inz the tide out of fa]t-marfhes, and whe- 
ther it will continue to flourifh notwith- 
fianding its being often wet with {alt 
water; alfo whether its roots are of that - 
nature which would bind andsmake more 
compact the earth thrown up to form 
fuck walls, and thereby enable them better 
to. refift the tide; or if they can name 
any other marine herb. or fhrub which 
wil. anfwer the fame end, they will 
greatly benefit the proprietors of falt 
marfhes, and contribute to the fafety of 
many diftricts which are liable to be over- 
flawed by the fea. I remain, Sir, your 
humble Servant. Hi. 8. 
Mark-Field, Nou. 22, 1798. 
, —— eee ae 
Fo the Editor of the Monthly Magazine. 
SIR, 
\, S. many people entertain inaccurate 
ideas concerning that moft import - 
ant and interefting invention the TELE- 
SCOPE, permit me briefly to {tate the fa&ts, 
as they appear tome, after fome invefti-: 
Lnvention of Tele[copes. 
[ Dec. 
gation, conducted, as T may fafely affert, 
with complete candour*, ae 
The minute Jabour of the ancient gems 
and medals fhews that the artifts poflefled 
fome magnifying power. But it feems 
uncertain whether this confifted in fimply 
lodging a drop of water in ahole, pierced 
through a thin piece of métal; orin fmall 
globes made of rock-cryftal. . 
Certain it is that {peftacles were un- 
known till about A. D. 1300: and from 
an epitaph given, I believe, by Tira- 
bofchi in.his “* Hifery of Italian Litera- 
ture,’ it is moft reafonable to infer that 
the invention belongs to D’Armato. of 
Florence. Venice being almof the only 
place where fine glafs was fabricated, in 
the middle ages, it is the more probable 
that Italv fhould claim the invention. 
About A.D. 1610, two children of 
Zachariah Janfen, a f{peétacle-maker of 
Middleburg in Zealand, amufing them- 
felves, difcovered that a concave and con- 
vex glafs, held ina certain manner, great 
ly magmified any objet. The father af. 
certained the invention by fixing the elaffes 
on a piece of wood at their proper dif- 
tances. 
The great Galileo, hearing very foon 
of this invention, improved it by putting 
the glafles into a tube ;« and is confidered 
as the father of the common telefcope, 
called alfo achromatic and retracting. 
That telefcope can hardly magnify 
above thirty times, becaufe that, as the 
{ize is augmented, the glafs muf be fo 
large and thick, as by the latter quality 
to injure the tranfiniffion of the light. 
This defeét was happily remedied by 
the grand invention of the REFLECTENG 
TELESCOPE, which may be enlarged te 
almoft any power; the effect arifing from 
metallic mirrors, which are fo placed and 
conftructed as to REFLECT an object 
magnified to an amazing degree. . 
Sir Ifaac Newton was the firft who 
made habitual ufe of the RefleQing Te- 
lefcope. That great man fuggefted fome 
improvements: but he acknowledges 
(Phil. Tranf. Nos. 80 and 83,) that the 
invention belongs entirely to James Gre- 
gory, a native of Aberdeen, and'after- 
wards profeflor of mathematics at St. 
Andrews. 
The work, in which Gregory firft de= 
{cribes his invention, is his ‘* Optica Pro- 
wota,’’ publithed, in 1663. In 1668 Sir’ 

* Dr. Prieftley’s ¢é¢ Hiffory of Optics,” one 
of the moft interefting works in any language, 
contains a circumftantial detail of the firft 
difcovery of teledcapes, &e. Editor. 
; Ifaac 
