402 Oliervalions on the peculiar Allernat'ions in ths Colour 



senger was quite new when we left this place, and hatl not been 

 used niore than five or six times." 



(Signed) G. E. Powell, First Lieut. 

 ShceriH'ss, Feb 9, 181 '3. £fig Cordelia. 



To Lieut. Sliuldham, &jc. 



Certijicaie. 

 I hereby certify, that I have seen Lieut. Shuldham's con- 

 trivance for the application of additional men to a capstan, when 

 it is required to have a great strain, and have no doubt of its 

 eiiicacy ; and as it is not attended with any tiouble or expense, 

 1 think the invention, when knou-n, will certainly be generally 

 adopted, its siniplicitv and utilitv being so obvious. 

 April 2ij, 1815. (Signed) A. Brown, Commander,R.N. 



Seferevce to the Engravirig of L?c?d. Sruldham's improved 

 Method of ivorkmg a Capstan. Plate V. fig. 2. 

 In addition to the usual manner of placing men between the 

 capstan bars, the ends of the bars should !;ave notches or gaps 

 made in them, in which an endless rope, A B, is received, and 

 passes through two pulley blocks, C D; thus forming two straight 

 lines, along which men being placed, can act by pulling the ropes 

 in the most efficacious n)anner upon the capstan. 



CV. Observations on the pea/liar ylltervaiions in the Colour of 

 Aviares, or the bright Star in the Heart of the Scorpion, com- 

 pared ivith that of other Stars. By Thomas Forster,£<;9. 



SiK, — 1 HAVE heretofore had occasion to notice the mutations 

 in the colour of the light of some of the larger fixed stars, and 

 have communicated such observations through the medium of 

 vour Magazine. I have now to commemorate the great, and, I 

 may sav, unusual 'urilliancv of this phsenomenon observed last 

 night in the star Antares, which has afforded an opportunity, 

 during the serenity of a long summer's night, of minutely observ- 

 ing and defining it, together with the concomitant twinkling. 

 ,\l)out 9-' 0.5' I firs; noticed it. The star twinkled a great deal ; 

 and this motion called twinkling, seems to consist of successive 

 dilatation and brigh'ness, and of apparent contraction and dull- 

 ness, alternating with each other. The alternating colours are 

 deep red and bright white with a tinge of blue. To be more 

 explicit, I have compared the red colour to the colour of cop- 

 per filings ignited with gunpowder in the pyrotechnical Jerbs, 

 and the white colour to ignited steel filings. The red colour 

 happens in general just at, or a little before, the maximum of 



tlie 



