1 82 Prof. Forbes's Researches on the Vibrations which take place 



will carry thee captive into captivity," i. c. will surely carry 

 thee captive, and HDV ^OVT [we-oteka atah), " cover thee 

 with a covering," i. c. surely, or completely, cover thee. And it 

 may be noticed, that a particular command thus to cover 

 the ark, seems to have been more needed than a command to 

 daub it with pitch, for navigation in early society is usually 

 performed in boats made of a single tree. It is after some 

 progress in the art, that men begin to cover within and with- 

 out with a covering of wood. 



I have made the above observations, assenting to the opinion 

 to which many would object, that a reference to the existing 

 productions of the climate in which the ark was built, may not 

 be irrelevant to such an inquiry, and believing it can be satis- 

 factorily shown from the Mosaic history of the Deluge, that, 

 in the opinion of its author, the upper strata of the earth have 

 not undergone those great and universal changes which some 

 attribute to the event, and that the present appearances of the 

 earth's surface are in correspondence with the history. 



I am, Gentlemen, yours, &c. 

 Temple Chambers, Jan. 1834. W. G. CARTER. 



XXXIII. Experimental Researches regarding certain Vibra- 

 tions which take place betweefi Metallic Masses having (liferent 

 Temperatures. By James D. Forbes,^^., F.R.SS. L. 8> Ed. 

 Professor of Natural Philosophy in the University of Edin- 

 burgh. 



[Concluded from p. 28.] 



2. Lifluence of Figure upon the Vibrations. 

 37. T HAVE already noticed the form of the apparatus 

 which I have generally employed. The time of the 

 oscillations and their magnitude depend upon the figure of 

 the vibrating mass, which seems to act just as in the case of a 

 pendulum, or rather of a rocking-stone, the impulse which it 

 receives at each vibration appearing to be given at whatever 

 instant of time the contact of the vibrating edges with the 

 block is effected. This, however, must be understood within 

 certain limits. There must be a decisive interval of time be- 

 tween the two contacts, for if the surface, instead of having 

 two solid angles, as in the bar described above, merges into 

 a continued curve, the vibrations will not take place. If, by 

 any means, however, the period of contact of two portions of the 

 curved surface with the block be prolonged, the impulse will 

 be obtained ; as in the case of a silver spoon, used as a bar, 

 where the bowl of the spoon rests upon the block. No vibrations 



