General physiology of muscles and nerves . Heavypendulums of this sort, called ballisticpendulums, are used for measuringthe speed of gun-shots. A magneticneedle which when suspended from athread assumes a direction from northto south, may be regarded as a pen-dulum in which, in place of the forceof gravitation, the magnetic attractionof the earth determines its positionin a certain direction. If a suddenpush is given to a pendulum of thissort, the force of the propulsion maybe calculated in this case also fromthe degree of deflection. If a con-tinuous electric current be conductedto a magneti
General physiology of muscles and nerves . Heavypendulums of this sort, called ballisticpendulums, are used for measuringthe speed of gun-shots. A magneticneedle which when suspended from athread assumes a direction from northto south, may be regarded as a pen-dulum in which, in place of the forceof gravitation, the magnetic attractionof the earth determines its positionin a certain direction. If a suddenpush is given to a pendulum of thissort, the force of the propulsion maybe calculated in this case also fromthe degree of deflection. If a con-tinuous electric current be conductedto a magnetic needle, the currentbeing parallel to the needle, the latterdeflects and assumes a position at an angle to the cur-rent, the magnitude of this angle depending on thestrength of the current. The magnetic needle assumesa new position, the repelling force of the current and themafjnetism of the earth counterbalancino each , however, the current, instead of acting continuously,acts only for a short time, the mngnetic needle suffers4. Fig 19. Measihe-mi;nt of smallangles of deflec-TION WITH JlIRKOllAND LENS. 58 PHYSIOLOGY OF MUSCLES AND NERVES. a push of but short duration and makes only a singlevibration, after which it returns to the position proper toit when at rest. The degree of deflection must in thiscase be proportionate to the strength of the current andto the brevity of its duration. If, therefore, the strengthis known and remains constant, the time occupied by thedeflection maybe calculated from its extent. Such de-flections are generally very slight. In order, therefore,to measure them with certainty, an apparatus which wasfirst applied by the celebrated mathematician Gaussis used. A small mirror o being connected with themagnet, a graduated scale s s, which is reflected inthe mirror, is read by means of a magnifying glass. Ifthe scale is placed parallel to the mirror when themagnet is at rest, and the magnifying glass is arrangedat right angles to the direction
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Keywords: ., bookcentury1800, bookd, booksubjectmuscles, booksubjectphysiology
