Method of adjusting Hadley's Sextant. 123 



5, a. cock which conveys the water by a pipe from the 

 reservoir to nearly the bottom of the boiler. 



4, a cock which stops the steain when the potatoe tubs 

 are taken off. 



5, a safety valve fixed upon the top of the boiler, loaded 

 with a weight of about four pounds to a square inch. 



6, a cock fixed in the side of the boiler to ascertalu 

 when it contains a proper quantity of water, 



T , one of the potatoe tubs detached from its lead vessel : 

 it is two fiect high, tv.enty inches wide at the top and se- 

 venteen ijiches at the bottom ; it will hold elcA-en stone of 

 potatoes. The boiler will steam sufficiently the four tubs 

 of potatoes in fifteen or twenty minutes time; and if the 

 whole are not in use, the lead pipes of those ]iot wanted 

 may be plugged up. Each tub and cover is held down by 

 tour levers, and an iron ball at the end of each lever. 



When the potatoes are sufliciently boiled by the steam, 

 the crane N raises and removes the tubs from their places 

 to the stone troughs U U, a section of one of which is oivcn : 

 the potatoes are thei-e bruised for use. 



XVI I r. A demonstraUe, accurate, and at all Times prac- 

 ticable Method of adjusting Hadley's Sextant so as to 

 render the Back Observation equally correct with the Fore 

 Observation ; and to measure an Angle of ] 50, 1 CO, or 

 1 70 Degrees, as accurately as one of 30, 40, or 50 De- 

 grees. Communicated to the Astronomer Royal by Letter 

 dated Sept. 28, 1S03. By the ii!<?y. Michael 'Waud, 

 of Tamworth, Staffordshire. 



JuLaVing several years used a Hadley's octant by Dollond, 

 of the common construction, to compute the lime from the 

 sun's double altitude, in order occasionally to examine the 

 rate of going of a gridiron pendulum clock, I have often 

 lost a number of observations from want of certain depend- 

 ence on angles above yo" : theflame inconvenience attcndid 

 all attempts at revising a table of parallaxes of stars above 

 43° meridional altitude; and also' all lunar distances above 

 go° required a more extensive instrument. The one I have, 

 however, being, from its tried accuracy, a great favourite, 

 it became more aru object with mc to invent s'.inie mode 

 of bringing this instrument to measure larger angles than 

 Qif than to purchase a more extensive one. Flattcrino; 

 myself that the subjoined experiments and obscrvaticms 



will 



