The mode of using it is by holding it perpendicularly, pecking it into the ground, and throwing out the loosened soil with the hands. In this way they can excavate with such rapidity, that a strong navvy, armed with the best spade, would not be able to keep pace with a black man armed only with his “katta,” or digging-stick.
In Africa the Digging-stick is used in exactly the same manner, and is generally made more weighty and effective by having a perforated stone fastened on the handle.
Here, again, man has been anticipated by Nature, and the savage of Australia or Africa digs in exactly the same manner as the common Heart-urchin of our shores, sometimes called the Hairy Urchin, in consequence of the number and fineness of the spines, which look just like hairs to the naked eye. The scientific name of this creature is Amphidotus cordatus.
Mr. Gosse, in his “Evenings at the Microscope,” gives so admirable an account of the mode of digging employed by the Hairy Urchin that I cannot do better than employ his own words. After describing the variety of structure of the different spines with which the shell is so thickly set, he proceeds as follows:—
“But what is the need of so much care being bestowed upon the separate motion of these thousands of hair-like spines, that each should have a special structure, with special muscles for its individual movement? The hairs of our head we cannot move individually: why should the Heart-urchin move his?”
“Truly, these hairs are the feet with which he moves. The animal inhabits the sand at the bottom of the sea in our shallow bays, and burrows in it. By going carefully, with the lens at your eye, over the shell, you perceive that the spines, though all formed on a common model, differ considerably in the detail of their form. I have shown you what may be considered the average shape, but in some, especially the finer ones that clothe the sides, the club is slender and pointed; in others, as in those behind the mouth, which are the largest and coarsest of all, the club is dilated into a long, flat spoon; while in the long, much-bowed spines, which densely crowd upon the back, the form is almost uniformly taper throughout, and pointed.”
“The animal sinks into the sand mouth downwards. The hard spoons behind the mouth come first into requisition, scooping away the sand, each acting individually, and throwing it outwards. Observe how beautifully they are arranged for this purpose, diverging from the median line, with the curve backwards and outwards.
“Similar is the arrangement of the slender side spines; their curve is still more backwards, the tips arching uniformly outwards. They take, indeed, exactly the curve which the fore-paws of a mole possess,—only in a retrograde direction, since the Urchin sinks backwards,—which has been shown to be so effective for the excavation of the soil, and the throwing of it outwards.
“Finally, the long spines on the back are suited to reach the sand on each side, when the creature has descended to its depth, and by their motion work it in again, covering and concealing the industrious and effective miner.”
The reader will notice that this mode of digging is exactly like that which is followed by the users of the Digging-stick, the earth being first broken up, and the loosened portions thrown aside. The whole of the description of the spines is exceedingly interesting, but, as it does not bear directly on the present subject, I cannot admit it into these pages.