Chief of all these is the fact that it is not what engineers call "dead-beat." That means that it will not go to the proper position and then remain there quite still. Instead, it will first slightly overshoot the mark, which being followed by the reverse action, it will come back and overshoot it just as far in the opposite direction. Instead, therefore, of a steady pointing, always in the same direction precisely, it will oscillate more or less, the exact north and south line being the mean or average position, the centre of the oscillations. It would of course be possible to damp this, to apply a break as it were, if the apparatus were to remain stationary. For example, if the whole concern were immersed in water the resistance of the liquid would restrain any quick movement of the axle, yet it would not prevent it from slowly finding its true position. Thus the oscillations would be reduced to such a small range as to be for practical purposes negligible. But the drawback to a device of that kind, applied to a gyroscope on board ship, would be that the axle would be carried round to some extent every time the ship turned. As she changed direction it would more or less carry round the water with it; that in turn would carry the gyroscope, and so the direction of the latter would be for a time untrue. It would in course of time regain its accuracy, but in the meantime it would be leading the ship astray. Consequently the application of this, in itself wonderfully simple, idea, to this extremely important purpose was accompanied with a difficulty which was for a long time insuperable. But all was overcome at last by the genius of Dr Anschutz, of Hamburg, whose firm were the first to turn out the practicable article. Taking advantage of another movement of the gyroscope when arranged as has been described, and using the revolving wheel itself as a centrifugal fan, he was able to make the wheel blow air "against itself," as it were, when in any position other than north and south. Thus, if it deviates towards the east, this jet of air tends to blow it back; if it turns westwards the jet again comes into operation, tending to bring the erring gyro back to its proper place; and so the tendency to oscillate is checked. The finished instrument as it is installed on the latest warships is, of course, quite different in detail from the simple contrivance which we have been considering so far, although it is the same precisely in principle. The essential part is a heavy metal wheel combined with which is an electric motor which keeps it rotating at a speed of 20,000 or so times per minute.