[ 527 J 



SUPPLEMENT. 



Methods of measuring minute Objects, of Daubenton, Luccock, Herschel. Actual 

 Measurements of various Specimens of clothing Wool. Inferences. Conditions 

 of accurate microscopical Comparison. Result of a comparative Trial between 

 Merino-Ryeland IVool and that of the Coronet and Alva Piles, in the Matiu^ 

 facture of Broad -cloth, and of a similar Comparison with R. X. S. Wool in that 

 of Casimir. Wool-produce per Acre on the Authors Farm in 1806. Probably 

 much short of its eventual Produce. Weight of the Fleeces of the Author's 

 Merino-Ryeland Rams sold to Mr. Birkbeck of Wanborough. Increase of 

 Weight and Value in his South Down Fleeces from one Cross of that Breed. 

 State of the same Cross as to Carcase. Carcase oj the Author's Ram-lambs in 

 1806. Statement oj his Lambing Account in 1807. Result of the Admini- 

 stration of Potatoes in iSo6 and iSoj. Conclusion, 



In various parts of the preceding Essay, I have had occasion to speak of the com- 

 parative fineness of the wool of different flocks of sheep, both of the pure and 

 mixed breeds. Those who are most accustomed to such enquiries will readily 

 confess how difficult it is to distinguish with the naked eye between the diameters 

 of objects so minute as the filaments of the finest Merino wool. This difficulty 

 has induced certain persons to render such examinations more decisive by means of 

 magnifying glasses. Daubenton, first of all the authors with whose works I am ac- 

 quainted, in a memoir on this subject presented to the French Academy of Sciences, 

 in the year 1779, proposes to measure the diameter of the several filaments by a 

 micrometer divided into squares of the 120th part of a French inch. The micro- 

 scope which he employed seems to have been of the compound kind, in which tb&; 



