An EXPLANATION of the SEVENTEENTH PLATE
The Scale of a Soal
ON drawing the Finger along the Skin of a Soal, from the Tail upwards, we shall
feel a Roughness that somewhat resists its Motion; the Cause of which will be ex-
plained by the Object now before us.
This Figure represents the Scale of a Soal, plucked from the Skin, and viewed through
a pretty large Magnifier. Its Shape is a Sort of oblong Square ; that End within the Skin
terminating circularly, and the other which comes out being armed with several sharp
Prickles ; every other of which A A A A is much longer than the intermediate ones
B B B B.
These Prickles are strong and sharp, and of a transparent Substance, having waved and
indented Ridges running from them, with Furrows or Channels between those Ridges,
appearing extremely pretty. The two outermost Prickles on either Side, c c, extend
wider than the Scale ; and the semicircular Line, from their Points round by the Letters
D, D, D, describes all that Part of it which rises out of the Skin, the other and much
greater Part sticking fast and being buried in it. The Number of Prickles differs according
to the Place whence the Scale is taken.
From the Middle of the Part above described, to the End of the Part within the
Skin, are a Number of small Quills or Pipes, E E E E, which probably convey Nou-
rishment to the whole. These diminish gradually in Length on either side towards the
Extremity, but spread, in Width, and form thereby a kind of fan-like Figure, which
seems as it were fluted.
The two Sides F F, consist of a more fibrous Texture, having numberless little
Ridges and Furrows, alternately, running parallel to each other, in a Curve-Direction at
either End, though nearly strait about the Middle. The whole Scale appears grisly and
transparent, but more particularly so in the little Channels between the Ridges: and all
the Scales are pretty much like this, but not exactly so ; for those growing on different
Parts of the Fish differ from one another as well in Size as in many other Particulars un-
necessary to mention here. G shews this same Scale about four times its natural Bigness.
PLATE XVII. FIG. 2.
A Piece of the Skin of a Soal
THE Skin being slead off from a pretty large Soal, and afterwards expanded and
dried, the Inside thereof appeared to the naked Eye very like a Piece of Canvas ;
but the Microscope discovered that seeming Texture to be nothing else but the inner Ends
of those curiously scallop'd Scales, which have been just now described in the former Fi-
gure : that is, the Ends of the Scales about E E E E were plainly visible by that Instru-
ment, on the Back-side of the Skin, lying over one another like the Tiles upon an House.
The Outside of the Skin presented nothing more to the naked Eye than the usual
Manner of arranging the Scales in a triangular Order ; but seen through a Microscope, it
exhibited a most curious and surprising Appearance ; the Scales A A A A, being deeply
fastened in the Skin B B, as the Figure before us shews.
As no Object is more common than the Scale of a Soal amongst those prepared in
Sliders, and sold by the People that make Microscopes, it is known almost by every Body ;
and the sharp prickly End is almost as generally imagined to be what sticks within the Skin,
and the other what comes out of it ; the quite contrary to which is here demonstrated to
The Skin and Scales on the Belly of a Soal are white, but on its Back of a greyish or
Lead-Colour : The general Structure of the Scale is, however, the same on both Back
and Belly, tho' there are particular Differences needless to be mentioned here ; but the
lead-colour'd ones on the Back are speckled very prettily with great Numbers of black
The Scale of a Perch, tho' of a different Figure, has a Number of sharp Prickles
standing out like those on the Soal's Scale.
There is almost an infinite Variety in the Scales of Fishes, which feem analogous to the
Feathers of Birds, and can't fail to afford Abundance of Entertainment and Satisfaction
to those who will take the Pains attentively to examine them.