of the Terrestrial Globe. 1809 



this temperature considered in the mass, and not at the sur- 

 face only, has not varied a hundredth part of a degree ! 



Irrespective of the vast importance of this result, we have 

 thought that curiosity would not be a little excited, in learning 

 how these two phenomena, apparently so distinct, — how the heat 

 of the earth, and the movement of a star, could mutually sub- 

 serve to a counter reckoning of their phenomena. But to make 

 this apparent, is an important object in the subsequent remarks. 

 It is also hoped and anticipated, that we may be able to present 

 an exact epitome of this difficult question to our readers, with- 

 out the aid of any abstruse calculations. 



Let us suppose then, that to each of the spokes of a common 

 wheel, such, for example, as that used in grinding, some heavy 

 body should be accurately fitted. Let us also suppose, that 

 these weights could easily glide along the spokes, in such a man- 

 ner that they might readily form a junction, whether it were 

 near the axis of rotation, or towards the outer circumference of 

 the wheel, or in any intermediate point. 



With a correct notion of this apparatus, we can easily conceive 

 that all the moving weights or masses, are placed, first near to 

 the axle, and we may inquire what force, applied to the handle, 

 will be necessary to give to the wheel the velocity of a revolu- 

 tion in a second. 



After this first experiment, let us move along each spoke, from 

 the centre to the circumference, the weight which is attached to it. 

 After this, the wheel will weigh neither more nor less than it did 

 before ; and yet to make it again move round with the velocity 

 of a revolution in a second, will require a much greater force. 



After having a correct apprehension of the apparatus in these 

 two conditions, it is scarcely possible that any one can question 

 the accuracy of the result above alluded to. At all events, the 

 simplest experiments can easily verify its truth. 



Since then, for the revolving of a wheel of a given weight with 

 a certain velocity, a force is required, greater in proportion as the 

 elements of which the total weight is composed are removed from 

 the centre, it is evident, for it is only the same result differently 

 expressed, that, under the action of a determinate force, the mo- 

 tion of the wheel will become slower in proportion as the difFe- 



