95. Tho’ from these Experiments it is manifest, that Fish die for want of constant Supplies of fresh Air in the Water, yet when taken out of the Water very lively, they soon die, notwithstanding the Surfaces of their Gills are then exposed to the immediate Contact of the Air; which shows that either the Air does not enter from the Gills to the Blood, from the open Air, as it does from the Water; or that the Circulation of the Blood is stopped by exchanging their proper Element, Water, for Air; as the Circulation of the Blood of Land Animals is soon stopped by immersing from Air into Water.
96. Hence we see the Benefit of frequently replenishing the Water with fresh Air, which we find is necessary not only to preserve the Life of Land Animals, but also of Fish; as also the Use of their Gills, to spread in thin Sheets fresh Supplies of Water, that they may the better come at the Air in the Water; for which Purpose both Sides of their Gills are furrowed with many fine Furrows, not only thereby to enlarge their Surfaces, but also more minutely to divide the Water, whereby to come at the Air in it.
97. Whence we may reasonably infer, how requisite it is, in order to keep the Blood in a salutary State, to have almost constant Supplies of the Breath of Life, fresh Air, to mix with it: For if the principal Use of the Gills were only to cool, and churn, and comminute the Blood, Water devoid of Air could as well perform that Office, as Water repleat with fresh Air. It must therefore be of Importance for all Animals to have so necessary a vital Fluid fresh and pure, and not foul and putrid.
98. A Fisherman informing me that the Fish were apt to die in the Well-boats, it occurred to me that it might, in a good measure, be remedied, by fixing upright a Board of a proper Breadth at the Outside of the Boat, as long as the Well is deep, on that side of the Well which is next to the Stern, and opening at an Angle of about 45 Degrees towards the Head; which, by checking the Course of the Stream of the River near the Boat, will raise the Water a little, and thereby cause it to run into the Well on that Side, and out on the other Side of the Boat; and the Run of the Water thro’ the Well, will be more accelerated, if a like Board is fixed in the same manner on the other side of the Boat at the Side of the Well next to the Head of the Boat, but opening towards the Stern at an Angle of 45 Degrees, by which means the Water will be lowered on this, as much as it is raised on the other Side of the Boat.——Another Means to have a brisker Current of Water thro’ the Well, would be to moor the Boat in a fixed Position across the Stream when it can conveniently be done. I am informed that there are Passages from Head to Stern, for the Water to pass freely thro’ the Fish-Well of some Vessels. We see, from the Event of the above Experiments, the Importance of frequently changing the Water in the Fish-Well of Ships, especially when there are many Fishes in it. Hence also we see how salutary it is to Fish, to have the Surface of the Water agitated into Waves by Winds, whereby Plenty of fresh Air enters, and is blended with the Water.
FINIS.
Transcriber’s Notes
A number of typographical errors were corrected silently.
New original cover art included with this eBook is granted to the public domain.