200 SOMK ACCOUNT OF A NKW LEVEL. 



The first was made three years ago ; the subject lias been 

 carefully digested since, and it is to be hoped tliat tliis will prove 

 a most valuable implement in the ordinary operations t>f horti- 

 culture long after the inventor has been forgotten. 



In appearance the instrument is something like half a brick. 

 Its dimensions are 3^ inches X 3^ x ^^^ 



The diagram represents the face of it, in which two cavities 

 are cut out so as to form each a quadrant of a circle, as appears 

 by the degrees marked. Some fine sand, like that used for hour- 

 glasses, is enclosed in these cavities by glazing in front. The 

 sand falls from the upper part through a small hole into the 

 lower, as in the conmion hour-glass. 'J'he particles of sand fall 

 so continuously that they form in appearance a tolerably fine 

 line. If the instnnnent be placed upon anything that is truly 

 horizontal the sand will fall, as a plunnnet would, from the small 

 hole in the centre, to 90^. But should the instrument be placed 

 upon anything that is not level, the particles of sand will still 

 fall perpendicularly, in accordance with the law of gravitation ; 

 but the apparently continuous line of falling sand will not be 

 direct from the centre to 90'' ; it will deviate from the latter 

 point in proportion as the object on which it may be placed de- 

 viates from being level. If it sliould be placed on the slope of 

 a rafter making an angle of 20^ with the ground, then the sand 

 will fall from the centre to 20'-' from the point at 90°. 



Again, if the instrument be placed with its side against an 

 upright post or stake, the sand will be seen falling in a line from 

 the centre to 90° ; if the post be not perfectly ui)right, then the 

 perpendicular stream of sand will be seen to fall on points more 

 or less distant from the line at 90°, according as the post is more 

 or less out of the perpendicular. 



In using this level for draining purposes, or for other inclined 

 planes, such as setting a melon-frame up to the sun so that its 

 roof may be of the same pitch as an adjoining pine-pit, first put 

 the level upon the rafter of the pine-pit or other inclined plane 

 to be copied, and mark the sand line, which we shall suppose to 

 indicate 75° ; then put the level on the rafter of the melon-frame, 

 and prop the frame until the sand line indicates the same angle. 

 And so of drains or other inclined surfaces, putting the level on 

 a piece of wood with parallel edges (a common straight edge). 



The level, if made of our Devonshire madrepore marble, is 

 expensive ; but, for ordinary purposes, the instrument does very 

 well made of oak or other well-seasoned wood. 



