8<)(5 H A It 
IIANCES, in a ship, are falls or descents 
oi the (ite rails, which are placed from the 
stern down to the gangways. 
HAND. See Anatomy. 
Hand-barrow, a wheelbarrow which is 
ot great use in fortification, for carrying earth 
from one place to another, and in a siege, for 
carrying bombs or cannon-balls along the 
trenches. 
Hand-breadth, a measure of three 
inches. 
Hand-cuffs, an instrument formed of 
two circular pieces of iron, each fixed on a 
hinge at the ends of a very short iron bar, 
which being locked over the wrists of a ma- 
efactor, prevents his using his hands. 
Hand-grenades. See Grenades. 
HARBINGER, an officer of the king’s 
houshold, having four yeomen under him, 
who ride a day’s journey before the court, 
when it travels, to provide lodgings. 
HARDENING, the giving a greater de- 
gree of hardness to bodies than they had be- 
fore. See the article Hardness. 
.There are several ways of hardening iron 
and steel, as by hammering them, quenching 
them, when hot, in cold water, case-harden- 
ing, &c. See Iron. 
HARDNESS, in bodies, a property di- 
rectly opposite to fluidity; by which they re- 
sist the impression of any other substance, 
sometimes in an extreme degree. As fluidity 
lias been found to consist in the motion of the 
particles of a body upon one another in con- 
sequence of a certain action of the universal 
fluid or elementary fire among them ; we must 
conclude that hardness consists in the absence 
of this action, or a deficiency of what is called 
latent heat. This is confirmed by observing 
that -there is an intermediate state betwixt 
hardness and fluidity, in which bodies will 
yield to a certain force, though they still 
make a considerable resistance. This is prin- 
cipally observed in the metals, and is the 
foundation of their ductility. It appears, in- 
deed, that this last property, as well as fluidi- 
ty, is entirely dependant on a certain quan- 
tity of caloric absorbed, or otherwise act- 
ing within the substance itself; for all the 
metals are rendered hard by hammering, and 
soft by being put again into the fire and kept 
there for some time. The former operation 
renders them hot as well as hard; probably, 
as Dr. Black observes, because the particles 
of metal are thus forced nearer one another, 
and those of fire squeezed out from among 
them. By keeping them for some time in the 
lire, that element insinuates itself again among 
the particles, and arranges them in the same 
manner as before, so that the ductility returns. 
By a second hammering this property is again 
destroyed, returning on a repetition of the 
heating, or annealing as It is called ; and so on, 
as often as we please. 
Hardness appears to diminish the cohesion j 
of bodies in some degree, though their fra- j 
gility does not by any means keep pace with ! 
their hardness. Thus, glass is very hard and I 
very brittle; but flint, though still harder 
than glass, is much less brittle. Among the 
metals, however, these two properties seem to 
be more connected, though even here the 
connection is by 7 no means complete. Steel, 
the hardest of all the metals, is indeed the 
most brittie; but lead, the softest, is not the ; 
most ductile. Neither is hardness connected 
VOL. I. 1 
H. 
S.G. 
- 
20 
3,7 
- 
19 
3,4 
- 
19 
3,3 
- 
19 
3,3 
- 
18 
3,2 
- 
17 
4,2 
- 
16 
3,5 
- 
13 
3,4 
- 
16 
3,8 
- 
17 
3,8 
- 
15 
4,2 
- 
14 
3,5 
- 
11 
2,8 
- 
12 
2,8 
- 
12 
4,4 
- 
12 
2,6 
- 
12 
2,6 
- 
12 
2,6 
- 
11 
2,7 
- 
1 1 
2,6 
- 
1 1 
2,7 
- 
11 
2,7 
- 
Q 
2,6 
- 
10 
3,6 
- 
10 
3,0 
- 
10 
2,7 
- 
10 
2,6 
3,7 
- 
10 
- 
8 
2,1 
- 
7 
3,5 
- 
6 
2,7 
- 
5 
2,3 
- 
3 
2,7 
H A R 
with the specific gravity of bodies; for a dia- 
mond, the hardest substance in nature, is little 
more than half the weight of the lightest me- 
tal. As little is it connected with the cold- 
ness, electrical properties, or any other qua- 
lity with which we are acquainted : so that 
though tire principle above laid down may be 
accepted as a general foundation for our in- 
quiries, a great number ot particulars remain 
yet to be discovered before w r e can offer any 
satisfactory explanation. 
All bodies become harder by cold ; but this , 
is not the only means of their doing so, for j 
some become hard by heat as well as cold. 
Mr. Quist and others have constructed j 
tables of the hardness of different substances. I 
The n ethod pursued in constructing these 1 
tables was by observing the order in which 
they were able to cut or make any impression 
upon one another. The following table, ex- 
tracted from M. Magell n’s edition of Cron- 
stedt s Mineralogy, was taken Irom Dr. Quist, 
Bergman, and Air. Kirvan. The first co- 
lumn shows the hardness, and the second the 
specific gravity. 
Diamond from Ormus 
Pink diamond 
Blueish diamond 
Yellowish diamond 
Cubic diamond 
Ruby 
Pale ruby from Brazil 
Ruby spinell 
Deep-blue sapphire 
Ditto paler 
Topaz 
Whitish ditto 
Bohemian ditto 
Emerald 
Garnet 
Agate 
Onyx 
Sardonyx 
Occid. amethyst 
Crystal 
Carnelian 
Green jasper 
Reddish-yellow ditto 
Schoerl 
Tourmaline 
Quartz 
Opal 
Chrysolite 
Zeolite r 
Fluor 
Calcareous spar 
Gypsum 
Chalk 
HARE. See Lepus. 
IIARIOT. See Hertot. 
HARMATTAN. The harmattan is a 
very singular wind, which blows periodically 
from the interior parts of Africa towards the 
Atlantic Ocean. The season in which it pre- 
vails is during the months of December, Ja- 
nuary, and February; it comes on indiscri- 
minately at any hour of the day, at any time 
of the tide, or at any period of the moon, and 
continues sometimes only a day or two, some- 
times five or six days, and it has been known 
to last fifteen and sixteen days. There are 
generally three or four returns of it every sea- 
son. It blows with a moderate force, but not 
quite so strong as tire sea-breeze. 
5 X 
H A R 
A fog or haze is one of the peculiarities 
which always accompany the harmattan. The 
English, Irench, and Portuguese forts at 
Y\ nydah, are not quite a quarter of a mile 
asunder, yet are frequently quite invisible to 
each other ; the sun, concealed the greatest 
part of the day, appears only about a few 
hours at noon, and then of a mild red excit- 
ing no painful sensation on the eye ! The 
particles which constitute this fog are depo- 
sited on the leaves of trees, on the skins of 
, e . . ne g roes > &c. and make them appear 
whitish. 1 r 
Extit me dryness makes another extraor- 
dinary property of this wind ; no dew' falls 
during its continuance; vegetables are wi- 
thered, and the grass becomes dry like hav. 
1 he natives take this opportunity to clear the 
Hue , by setting fire to the trees and plants 
vvhfle m that dry and exhausted state. The 
dryness is so extreme, that the covers of 
bonks, even closely shut up in a trunk, are 
bent as if exposed to the fire. Houshold fur- 
lnUue is much damaged ; thepannels of wain- 
scots split, and fineered work flies to pieces 
1 he joints of a well-laid floor of seasoned wood 
open sufficiently to admit the breadth of a 
. finger between them ; but become as close as 
i before on the ceasing of the harmattan. The 
! Jl £ man ‘ Jod -V d °es not escape the parching 
! eft ects of tins wind; the eyes, nostrils, lips, 
: and palate, are rendered dry arid uneasy; the 
| lips and nose become sore, and though the 
air is cool, there is a troublesome sensation of 
pricking heat on the skin. If the harmattan 
continues four or five days, tiie scarf-skin 
peels oh, hist from the hands and face, and 
afterwards from the rest of the body. 
l*‘Ough this wind is so fatal to vegetable 
life, and occasions these troublesome effects 
to the human species, it is nevertndess highly 
conducive to neaitii ; it stops tiie progres. of 
epidemics, and relieves the patients labouring 
under fluxes and intermittent fevers. Infec- 
tion is not easy, at that time to be communi- 
cated, even by inoculation. It is also remark- 
able for the cure of ulcers and cutaneous dis- 
eases. ircon. of Nat. b. 5. 
HARMONICA. I his word, when origi- 
nally appropriated by Dr. Franklin to that 
premia] form or inode of musical glasses, 
which he himself, after a number of happy 
experiments, had constituted, was written 
Armonica. It is derived from the Greek 
word i^ovia. The radical word is «* fEly to 
suit oi lit one thing to another. Relations or 
aptitudes of sound, in particular, were under- 
stood by it; and in this view. Dr. Franklin 
could not have selected a name more expres- 
sive of its nature and genius for the instru- 
ment which we are now to describe; as, per- 
haps, no musical tone can possibly be finer 
nor consequently susceptible of juster con- 
cords, than those which it produces. 
“ y r - I’uckridge, a gentleman from Ireland, 
was, says Dr. Franklin, “the first who thought 
ot playing tunes formed of these tones. He 
collected a number of glasses of different 
sizes ; fixed them near each other on a table ; 
and tuned them, by putting into them water, 
more or less as each note required. The 
tones were brought out by pressing his fin- 
gers round their brims. II e was unfortunate- 
ly burnt here, with his instrument, in a fire 
which consumed the house that he lived in. Mr. 
E. Deleval, a most ingenious member of our 
royal society, made one in imitation of it. 
