In certain types living on clamp soil, the rhizoids penetrate the substratum, and in addition to fixing the plant absorb food substances (dissolved salts) from the substratum (fig.
Each cylinder has a platinum wire fused to the upper circumference to connect with a clamp from which a wire leads to the proper pole of the battery.
The needle b is then substituted for a, there being now no needle in the clamp attached to the microscope arm, and the difference between the reading now obtained and the dip, together with the weight added to the needle, gives the product of the moment of the needle b into the earth's total force.
C is the clamp and M the slow motion in position angle.
The clamp around her released.
K is the clamp in position angle, P the slow motion screw in position-angle; pp is the position circle, R, R its two readers.
The long arm f serves to clamp the telescope in zenith distance and to communicate slow motion in zenith distance when so clamped.
The tube V, on the contrary, is attached to the cradle, and merely forms a support for the finder Q, the handles at f and p, and the moving ring P. The latter gives quick motion in position angle; the handles at p clamp and give slow motion in position angle, those at f clamp and give slow motion in right ascension and declination.
In another system introduced by the Mannesmann Tube Company the prop is made up of weldless steel tubes sliding telescopically one within the other, which are fixed at the right height by a screw clamp capable of carrying a load of 15 to 16 tons.
But they are weak, and modern experience goes to show that a strong concrete is the best, and that probably materials like broken clamp bricks or burnt clay, which are porous and yet strong, are far better than cinders as a fireproof aggregate.