336 Miscellaneous Intelligence. 



less, not attracted so largely the attention of the scientific world 

 as might have been expected. Their advantages, however, are 

 as unexceptionable as those resulting from the diagonal trusses ; 

 and there can be no question but the longitudinal strength commu- 

 nicated by the latter would be considerably diminished, if the 

 lateral strength atForded by the former were removed, or in any 

 degree impaired. Hence," continues Mr. Harvey, *' without an 

 intimate and perfect union of the advantages resulting from both, 

 and which can alone be done by the perfect application of Circular 

 Sterns^ the separate strengths afforded by the two can never be 

 effectually united." 



To this important argument the author adds the no less im- 

 portant one, that, " in ships with square sterns, the application of 

 the diagonal system of trusses does not produce its maximum effect, 

 nor is the continuity of the shelf-pieces preserved, since the most 

 abrupt termination of them takes place at the tjuarters, a difficulty 

 entirely removed in the circular form, by the happy introduction of 

 the Ekeing, and affording a perfect illustration of the term 

 * internal hoop,' so appropriately applied to them by Sir Robert 

 Seppings." 



II. Chemical Science. 



1. Apparatus for exhibiting the Simultaneous Rotation of tioo 

 Voltaic Conducting Wires round the opposite Poles of Magnets. — 

 An apparatus of this description was constructed some time ago 

 by Mr. T. Griffiths, and shewn at the London Institution during 

 a course of Lectures on Electro-magnetism, delivered in 1823 by 

 Professor Brande. It consists of two copper wires suspended in 

 the usual manner, and dipping into a shallow vessel of mercury, 

 in which are placed two bar magnets with their opposite poles 

 arranged above its surface. The connexion being established 

 between the battery and the apparatus, the wires revolve round 

 the magnets simultaneously, but in opposite directions. In this 

 form of apparatus the necessity of stopping the single rotation 

 to exhibit its contrary movement by reversing the magnet is 

 avoided. 



2. On the mutual action of Magnetic and Unmagnetic Bodies. — 

 Extract from the proceedings of the Academy of Sciences of 

 Paris, March 7, 1825. — *' M. Arago placed before the Academy 

 an apparatus, shewing, in a new form, the mutual action of mag- 

 netic and unmagnetic bodies. In his first experiments he had 

 proved that a plate of copper, or of any other solid or liquid 

 substance, placed under a magnetic needle, exerted on it an action 

 which had for its immediate effect an alteration in the amplitude 

 of its oscillations without sensibly changing their duration. The 



