In the next sections he shows that the penetrating and magnifying 

 powers, so far from assisting each other, will often prove reciprocally 

 detrimental, which he thinks may be explained by admitting that 

 while the light collected is employed in magnifying an object, it can- 

 not be exerted in giving penetrating power, to which perhaps ought 

 to be added the detrimental effect of the magnifying power on the 

 heterogeneous ingredients floating in the atmosphere. Whatever be 

 the cause, the fact is proved by various observations. 



Lastly, he shows that as we must not limit our vision within the 

 sphere of the single stars, we must call the united lustre of the sidereal 

 system to our aid in stretching forward into space. Supposing one 

 of these clusters of 5000 stars to be at one of those immense distances 

 to which only a 40-feet reflector can reach, he calculates that this 

 distance will exceed at least 300,000 times that of the most remote 

 fixed star visible to the naked eye. He concludes with a rough cal- 

 culation how much time it would take to sweep the heavens with a 

 penetrating power of such an immense extent ; and finds that in this 

 climate, with his 40-feet reflector, with a magnifying power of 1000, 

 this operation for the whole sphere would take no less than 811 

 years. 



A second Appendix to the improved Solution of a Problem in physical 

 Astronomy, inserted in the Philosophical Transactions for the Year 

 1798, containing some further Remarks, and improved Formulas for 

 computing the Coefficients A and B ; by \vhich the arithmetical Work 

 is considerably shortened and facilitated. By the Rev. John Hellins, 

 B.D.F.R.S. and Vicar of Potter's Pury in Northamptonshire. Read 

 Dec. 12, 1799. [Phil. Trans. 1800, p. 86.] 



This paper relates to an improved solution of a problem by which 

 swiftly converging series are obtained, which are useful in computing 

 the mutual perturbations of the planets ; and contains some further 

 remarks andim 

 the arithmetic 



iproved formulsefor computing the coefficients, by which 

 al work is considerably shortened and facilitated. 



Account of a Peculiarity in the Distribution of the Arteries sent to the 

 Limbs of slow-moving Animals ; together with some other similar 

 Facts. In a Letter from Mr. Anthony Carlisle, Surgeon, to John 

 Symmons, Esq. F.R.S. Read Jan. 9, 1800. [Phil. Trans. 1800, 

 p. 98.] 



This peculiarity was first observed in the axillary arteries and in 

 the iliacs of the Lemur tardigradus, which at their entrance into the 

 upper and lower limbs were found to be suddenly divided into a con- 

 siderable number of equal-sized cylinders, which occasionally anasto- 

 mosed with each other, and were regularly distributed on the mus- 

 cles ; whilst the arteries proceeding to the other parts of the body di- 

 vided in the usual arborescent form. 



Upon prosecuting this inquiry, it was found that the Bradypus 



