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MINUTES OF PROCEEDINGS OF 
The Pendulum Proper (Plate I). 
2. Consists of a strong brass plate a } bearing a limb o graduated on 
silver from 0° to 150°. An opening in the centre of this plate admits of 
the adjustment of the axis of suspension d of a pendulum b, formed of a 
steel rod h with collar and brass bob c 3 into which bob a small plug of soft 
iron is inserted. The axis of the pendulum is perpendicular to the face of 
the plate. This pendulum consists of two parts, the steel rod bearing the bob, 
and an index needle /, fixed through a collar to an iron washer or circular disc /. 
A forked spring Jc, presses the collar of the needle against the collar of the 
pendulum rod. The result of this arrangement is that when the pendulum 
rod is put in motion it carries the needle with it, and the whole oscillating 
system consists then of the pendulum rod with its bob and collar; the 
needle with its bob, collar, and iron washer; and the axis of suspension or 
prolongation of the pendulum collar. 
An opening towards the side of the brass plate admits the adjustment of a 
straight electro-magnet r. At the centre opening, immediately behind the 
iron washer, a strong horseshoe electro-magnet u is fixed, so that when the 
oscillating system is set in motion the poles of the magnet are extremely 
close to the posterior face of the iron washer/. A base of wood X supports 
the whole apparatus; this base is provided with levelling screws YY a 
pressure screws WW, to establish communication with the electro-magnets; 
and a spirit-level Z perpendicular to the face of the instrument. 
The vernier of the needle is graduated to read the of 1°, or 3 minutes. 
The Conjunctor (Plate II). 
3. Consists of two upright brass rods bb, upon which a straight electro¬ 
magnet a is made to slide. Each of these rods is furnished at its lower 
extremity with a pressure screw d, to establish communication with the 
electro-magnet; the electric current arrives by one rod, magnetizes the 
electro-magnet, and returns by the other rod. 
Under the electro-magnet is a small iron cup f connected with a pressure 
screw bv a strip of copper Jc. In this cup a little mercury is placed. The 
height of this mercury can be regulated by a screw g, with a divided head o. 
To another pressure screw a steel blade l is attached, carrying a pin which 
can be placed exactly over the orifice in the iron cup. The cup is sur¬ 
rounded with a movable brass cylinder /, which can be taken off to examine 
the mercury, &c. A leaden weight r with a soft iron head completes the 
conjunctor. 
The Disjunctor (Plate III). 
4. Two straight springs aa are mortised into two pressure screws. A 
small screw b , with platinum point, is inserted into the free extremity of each 
of these springs. Two other screws, with platinum points, are arranged in 
brass supports c, so that their points are presented to the points of the 
spring screws. The supports c are furnished with pressure screws. 
