MAR ■ mas 
most celebrated mathematicians and op ti- ter.” “ Appendix to the Use of the Globes/ 
cians of his time. He first taught a school 
in the country ; but afterwai'ds came up to 
London, where he read iectiives on experi- 
mental philosophy for many years, and car- 
ried on a very extensive trade as an opti- 
cian and globe-maker in Fieet-street, till 
the growing infirmities of old age compelled 
him to withdraw from the abtive part of 
business. Trusting too fatally to what he 
thought the integrity of others, he unfortu- 
nately, though with a capital more than suf- 
ficient to pay all his debts, becume a bank- 
rupt. The unhappy old man, in a moment 
of d_esperation from this unexpected sti oke, 
attempted to destroy himself; and the 
wound, though not immediately mortal, 
hastened his death, which happened the 9th 
of February, 1782, at 78 years of age. 
He had a valuable collection of fossils and 
curiosities of almost every species; which, 
after hia death, were almost given away by 
public auction. He was indefiitigable as 
an ar tist, and as a writer he had a very 
happy method of explaining his subject, and 
wrote with clearness, and even consider- 
able elegance. He was chiefly eminent in 
tire science of optics ; but he was well skil- 
led in the whole circle of the mathematical 
and philosophical sciences, and wrote useful 
books on every one of them ; though he was 
not distinguished by any remarkable inven- 
tions or discoveites of his owi». His publi- 
catiojis were very numerous, and generally 
nseful ; some of the principal of them were 
as follows : 
“ The Pbilofophical Grammar; beluga 
View of the present State of Experimental 
Physiology, or- Natural Philosopliy,” 1735, 
8vo. “ A New, Complete, and Universal 
System or Body of Decimal Arithmetic,” 
1735, 8vo. “ The V'oung Student’s Me- 
morial Book, or Pocket Library,” 1735, 
8vo. “ Description and Use of botii the 
Globes, the Armillary Sphere, and Orrery, 
Trigonometry,” 1736, 2 vols. 8vo. “ Sys- 
tem of the Newtonian Philosophy,”. 17,59, 
3 vols. “ New Elements of Optics,” 1759. 
“ ?i'Iathemat,ica! Institution.s,” 1764, 2 vols. 
“ Pliilologic and Philosophical Geography,” 
1759. “ Lives of Philosophers, their In- 
ventions, &c.” 1764, 3 vols. “ Miscellane- 
ous Correspondence,” 1764, 4 vols. “In- 
stitutions of Astronomical Calculation,” 3 
parts, 1765. “ Introduction to the Newto- 
nian Philosophy,” 1765. “ Treatise of 
Logarithms.” “ Treatise on Navigation.” 
“ Description and Use of the Air-pump.” 
“ Description of the Torricellian Barome- 
“ Phllosophia Britannica,” 3 vols. “ Prin- 
ciples of Pump-work.” Theory of the 
Hydronteter.” “ Description and Use of a 
Case of Mathematical Instruments.” “ Dit- 
to of a universal .Sliding Rule.” “ Micro- 
grapliia, or the Micr oscope.” “ Principles 
of Perspective.” “ Course of Lectures.” 
“ Optical Essays.” “ Essay on Electricity.” 
“ Essay on Visual Glasses, or Spectacles.” 
“ Hor'ologia Nova, or New Art of Dialling.” 
“ Theory of Comets.” “ Nature and Con- 
struction of Solar Eclipses.” “ Venus in 
the Stm.” “ The Mariner’s Mirror.” “Ther- 
mornetrum Magmim.” “ Survey of the So- 
lar System.” “ Essay on Island Crystal.” 
“ Logorithniologia Nova,” &c. &c. 
MARTYNIA, in botany, so named in 
bonoitr of John Martyn, F. R. S. professor 
of botany at Cambridge, a genus of the Di- 
dynamia Angiospermia class and order. Na- 
tural order of Personal a-. Bignonim, Jus- 
sieu, Essential cliaracter : calyx five-cleft ; 
corolla rhigent ; capsule woody, corticate, 
with a hooked beak, four-celled, two-valved. 
There are six species. 
MARTLETS, in heraldic, little birds re- 
presented without feet, and u,3ed as a differ- 
ence or mark of distinction for younger 
brothers, to put them in mind that they are 
to trust to the wings of virtue and merit in 
order to raise themselves, and not to their 
feet, they having little land to set their foot 
on. 
MASON, a person employed under the 
direction of an architect in the raising of a 
stone building. Tlie chief busine.<is of a 
mason is to make the mortar ; raise the walls 
from the foundation to the top, with the 
necessary retreats and perpendiculars; to 
form the vaults, and employ the stones as 
delivered to him. IFhen the stones are 
large, the business of hewing or cutting 
tlicra belongs to the stone-cutters, though 
these are frequently confounded with ma- 
sons; the ornaments of sculpture are per- 
forme<l by carvers in stones or sculptors. 
The tools or implements principally used 
by them are the square, level, plumb-line, 
bevel, compass, hammer, chissel, mallet, 
saw, trowel, &c. Besides the common in- ■ 
struments used in the hand, they have like- 
wise machines for raising of great burdens, 
and the conducting of large stones, the 
principal of which are the lever, pulley, 
wheel and axis, crane, &c. See Leves, &c. 
Masons, /i’ee andiaccepled, a very ancient 
society or body of men, so called, cither 
from some e-xtraordinary knowledge of 
