General Notices. 



279 



the bright plates, at such an angle as permitted vision of objects through 

 them, this recalled Mr. Taylor's suggestion, and showed how it might be 

 made available for copying natural flowers and other small objects." 



" Fig. 44. represents a piece of thin plate-glass (a d e f), set upright on a 

 drawing-board by means of a wooden standard (a b c), in a groove in which 

 the edge of the plate is retained by the wedges g and h. The wooden 

 standard is not fixed to the drawing-board, and may be set on it in any con- 

 venient position. To use this apparatus, it is placed in front of the artist, 



45K -s 1 



Fig. 44. 



Camera lucidafor Gardeners- 



with the standard a b c towards him ; the object to be copied is laid on the 

 left-hand side of the plate, as at o ; the head of the observer being also a 

 little to the left of the pillar, and the eye directed towards the middle of the 

 plate, as at m, a distinct image of the object o will be perceived, as if it lay 

 on the paper at p ; and as, at the same time, a pencil held on the right-hand 

 side of the plate will be equally visible, it may be applied to trace the image at p. 



" Some attention is required in selecting a favourable position for the ap- 

 paratus, in respect to the illumination of the object, and its admitting only 

 such a degree of light to the paper on the right-hand side of the glass, as 

 may give sufficient distinctness to the point of the pencil, by which precaution 

 the reflected image is seen to most advantage." 



" It must be recollected, that the delineation will not represent the ori- 

 ginal object as beheld by direct vision by an eye placed at i, being that of 

 a reflected image, similar to what would be seen by direct vision, if the 

 eye had been situated at k." (Mech, Mag,, vol. xxxiv. p. 202.) 



Kyanised Timber. — -In a series of experiments carried on at Welbeck dur'np- 

 the last four years, regarding the efficacy of kyanised timber for gardenin"' 

 purposes, we have not found it last longer, when exposed to great heat and 

 moisture, than the unprepared. In 1838 His Grace the Duke of Portland first 

 published the results of a trial in a Calcutta stove, the bottom-heat being sup- 

 plied by steam, and the prepared and unprepared timber plunged in the tan, 

 subjected to a heat of from 90° to 100° Fahrenheit; good Memel deal un- 

 prepared lasted longer than the best oak kyanised. The then managing 



