60 Analyses of Books, [Jan. 



Article XIV. 

 Analyses of Books. 

 • 4. Philosophical Transactiofis for the Year 1821. Part TI. 



This part of the Philosophical Transactions contains fifteen 

 jMipers, the first of which is : 



J. An Account of Experiments to determine the Times of Vibra- 

 iions of the Pendulums in different Latitudes. By Capt. Edward 

 Sabine, of the Royal Regiment of Artillery, FRS. and FLS. 



For the important communications made by Capt. Sabine to 

 the Royal Society, a Copley medal has been awarded to him. 

 Of this elaborate paper it will be impossible to give even a sketch, 

 for the results of the experiments are contained in upwards of 

 fiO tables, some of which are of great length. The precau- 

 tions which were taken to ensure accuracy will be best learned 

 from Capt. Sabine's own words. He commences his paper by 

 stating, that " the clocks and pendulums used in these experi- 

 ments^ are the property of the Royal Society, and were prepared 

 by their direction under the immediate superintendance of Capt. 

 Kater, who, in a manuscript account presented to the Royal 

 Society, of the instruments furnished to the expeditions on the 

 northern discovery, has described them as follows : 



" * The clocks were made by Shelton, and are the same which 

 accompanied Capt. Cook round the world : for each clock, a pen- 

 dulum was cast in one piece of solid brass : this was furnished 

 with a knife edge of hard steel, perfectly straight, and finished by 

 drawing the edge longitudinally two or three times on a soft 

 hone, so as to take from its sharpness, and thus preclude any 

 alteration from wear ; the back of the knife edge bore firmly 

 against a stout cross piece, and the heads of the screws secur- 

 ing it, were sunk below the surface, and concealed by brass pins, 

 to prevent their being removed : the knife edge was carefully 

 adjusted, so as to be at right angles to the direction of the gra- 

 vity : a very firm support of brass was screwed to the thick plank 

 which forms the back of the clock case ; in this were imbedded 

 two pieces of agate, which were ground into portions of hollow 

 cylinders, finished in the places to receive the knife edge of the 

 pendulum : parallel to the agates, a small level was fixed in the 

 direction of the cylinders, by means of which they could be 

 placed truly horizontal : an arc divided into degrees and tenths, 

 but which might be read oft' by estimation to hundredths, was 

 attached to the back of ihe clock case at the bottom of the pen- 

 dulum, to give the arc of vibration. 



** * Each clock was furnished with atriangularsupport of wood 

 contrived by Dr. WoUaston, and so firmly arranged that there 

 appears no reason to apprehend any motion in the point of sus- 



