Mr. W. NisBET exhibited specimens of the fruit of Pekea guianemis, 

 now selling in the markets of the town, and in many respects found 

 preferable to the common Brazil nut ( Bertholletia excelsa). Also a 

 cocoa nut, in a state of germination. 



The following papers were read : — 



ON TIME-BALLS AND SYMPATHETIC CLOCKS, 

 By John Hartnup, Esq., F.R.A.S., etc. 



There appears to be some doubt to whom we are indebted for the 

 first application of electro-magnetism as a maintaining power to clocks. 

 Mr. Alexander Bain had applied it in 1 842 ; but the attractive and 

 repulsive forces of the magnets were, at that time, brought to bear 

 directly on the pendulum — a method fatal to accurate performance, since 

 batteries of unvarying power cannot be obtained. 



The electric clock, which I recently saw at the Royal Observatory, at 

 Greenwich, was constructed by Mr. C. Shepherd, of Leadenhall-street, 

 London. In this clock, the maintaining power is transmitted to the 

 pendulum by a spring, so that the varying power of the batteiy is not 

 communicated directly to the pendulum. 



Galvanic currents can, however, be transmitted along a conducting 

 wire, either by an electric clock or by an ordinary astronomical clock, 

 and, by causing the currents thus transmitted to excite magnets, the 

 hands of any number of clocks, placed in the circuit, may be made to 

 move simultaneously with the hands of the primary clock. 



At Greenwich, the clock which transmits galvanic currents is an 

 electric clock, and it is made to show correct time by a mechanical 

 action on the pendulum. At each vibration towards the right, the 

 upper part of the pendulum-rod comes in contact vdth a pin, and 

 thereby completes the circuit ; as the pendulum vibrates towards the 

 left, the contact is broken ; therefore, the primary clock causes the trans- 

 mission of a galvanic current once during two oscillations of the pendu- 

 lum. Each secondary clock is provided with an electro-magnet, which 

 becomes animated during the transmission of a galvanic current, and 

 draws its armature towards its poles : when the contact is broken, the 

 armature is made to fall back by the force of gravity. In this way the 

 pallets are made to oscillate, and this oscillatory motion is communi- 

 cated to the seconds arbor, and thence to the minute and hour hands, 

 by the ordinary system of wheels. 



At present the primary clock at Greenwich gives motion to five 

 secondary clocks, four of which are on the premises, and one is in the 

 Electric Telegraph Ofiice, at London Bridge, a distance of five miles 



