438 



The Earl of Rosse on the Radiation of 



[May 27, 



This apparatus has not yet had a fair trial, as I was unable to obtain 

 from Messrs. Elliot a pile ready made of similar dimensions to that which 

 I already possessed. That which they sent had only one-fourth the re- 

 quired area of face. 



The followiug is a summary of the results : — 



Reference number. 



Date of observation. 



Mean error. 



Moan deviation. 



Deviation (calcu- 

 lated). 



Observed deviation 

 reduced to full 

 moon. 



i c 



m S3 



~ X 

 w c 



x — 



§1 



H 



x 5 



Mean altitude of 1 

 moon. 



Number of read- 

 ings. 





I. 

 II. 



1868. 

 Dec. 30. 

 „ 31. 





1037 

 85-1 



94-1 



85-8 



110 



99-2 



o 



19 

 33 









III. 

 IV. 



V. 



VI. 



vn. 

 vm. 



IX. 



X 



XI. 



XII. 

 XIII. 



XIV. 



XV. 

 XVI. 



1869. 

 Jan. 1. 

 „ 21. 



» 26. 



Mar. 23. 

 „ 27. 



„ 28. 

 „ 31. 



April 14. 

 „ 17. 



19. 



„ 20. 

 i] 22. 



n 24. 



„ 25. 



34 

 49 



35 



27 



43 

 85 



38 



28 

 45 



67-5 

 34 



83 



57 

 115 



113 

 17 



13-1 



35-5 

 33 



121 



84 

 88-4 



73-1 

 419 



96-7 



67-7 



99-6 



96-1 

 62-8 



8-3 



16-6 



36-3 

 48-8 



75-5 



95-3 

 99-4 



92-1 

 81-1 



85-8 



84-2 

 115 



117 

 27-7 



79 



96 

 68' 



88-2 

 88-8 



47 

 79 



15 



57 



5 



16 



58 



123 



110 



85 

 72 



45 



18 

 6 



o 



56 



35 

 30 



18 



27 



25 

 35 



30 

 25 



... 

 40 



15 



49 

 31 



4 



65 



14 

 51 



15 



29 



66 



Occasional clouds. 



f White frost. Mirrors became 



j dewed ; but the readings 



] taken after this took place 



\^ have been rejected. 



Occasional clouds. 



f Occasional clouds, strong 



| gusts of wind. 



J No note of cloud, very little 



\ breeze, generally calm. 



' Moon low, sky covered, with 

 hazy clouds, through which 

 themoon was seen withmuch 

 diminished brilliancy. 



"Very clear and calm, but 

 moon low; no perceptible 

 impulse imparted to the 

 needle. 



' "Wind blowing strong into 



• the mouth of the tube nearly 

 the whole time. 



' No note of cloud till just at 



• the end of these observa- 

 tions. 



f A very little wind ; occasional 



1 r»l nn r\ a 



^ L-1ULLU.O. 



( Halo with hazy clouds ; 

 j moon seen through them 

 j with much-diniinished bril- 

 ls lianey. 



[ Frequent passing clouds du- 

 \ ring the latter part of these 

 [ observations, 

 f No cloud visible, but haziness 

 I suspected, as it existed both 

 [ at sunset and at sunrise. 



1 



2 



3 



4 



5 



6 



7 



8 



9 





