MlCTiOMETER MEASURES. 23 



some parts were much sooner fit for hoeinrg than oth-ers. Cultivation of 

 The person that hoed them was sometimes not employed ^"rneps, by Mr. 

 , , , . , , , . , William Wat- 



among them above an hour in the day ; which prevents my ^on. 



furnishing an accurate account of the expense of hoeing each 

 ridge. 



So easy is the operation of hand-hoeing the small ridges or 

 drills with broad intervals, that in this quarter, it is nearly ali 

 performed by women, boys, and girls. If w^e depended on 

 -«nen, as the farmers do in some other districts, we could not 

 perfectly hoe much more than one third of our turnip crops. 



I am. Sir, 

 Your most obedient Servant, 



W, Watson. 



North Middletorit near VFooler, 

 by Bel/or d, Northumberlandg^ 

 Feb.l^th, 1804. 



On Comparative Microtneter Measures. In a Letter from 

 the Rev. Dr. J. A. Hamilton, Dtan of Cloyne, to the 

 Rev. J. Brinkley, F.R.S.* 



Observatory J, Armache Jan. 10, 1806. 

 DEAR SIR, 



BEG leave, through you, to communicate to our Academy Three methods 

 the following paper, on comparative observations made with °^ measuring^ 

 different kinds of micrometers ; which, I hope, may be deemed the' wire mi- 

 worthy their notice. It was suggested to me, so long since as crometer ; di- 

 in the year 1794, that a comparative view of the result of the J\^^ .\^^ ^j^^i 

 measures, made under similar circumstances, of the diameters sextant.j 

 of the heavenly bodies, with the different kinds of micrometers, 

 that are now most generally used by astronomers, might have 

 considerable use ; as well in confirming the determinations of 

 the values of the diameters, as given by former observations, 

 9S in deciding on the merits of the different instruments, and 



* Irish Transactions, vol. X. 



