OF SURVEYING INSTRUMENTS. 69 



Boatillg OF Yachting Pocket Compasses, with floating dials and gimbal movement, 

 by which the dial is always perfectly horizontal : 



482. Gimbal Pocket Compasses, with chrysolite cap and floating card, in round polished 



metal cases with lid ; size of compass card : 



ij^-inch. ij^-inch. 2-inch. 2^-inch. 3-inch. 



14s. 6d. 15s. 6d. 17s. 6d. 100 130 



If silver-plated 3s. to 7s. extra. 



483. Boating Compasses, richly gilt, in morocco case, about If-inch. diameter 18 6 



484. BOATING COMPASSES, silver-plated . . . . 15 6 



485. GILT GIMBAL COMPASSES, in mahogany case, very excellent and reliable for 



boating or yachting purposes (fig. 485), p. 67 . . 17 6 



486. Singer's Patent Compass, for bad light or defective vision, this arrangement 



consists of a white or mother-of-pearl card plate, having one half painted 

 black, with the usual divisions (fig. 486), p. 67 ; the effect in obscure light is 

 very striking, the points being clearly visible in the darkest night ; it is applied 

 to the boating, pocket, or any of the preceding compasses at a slight extra 

 cost, pocket sizes for travellers, 7s. 6d. ; 12s. 6d. ; and . 110 



487. SINGEE'S PATENT COMPASSES, boating sizes, in neat polished mahogany cases 



with jewelled centres, very superior and sensitive, 4f inch, outside 1 12 



488. SINGER'S PATENT COMPASSES, boating sizes, 4^ inch, outside . 180 



489. Larger sizes in brass, for boats or ships, with best needle and agate cap, 1 4s. ; 



2 2s.; and 330 



490. Trinket Compasses, in form of lockets, globes, half globes, with gimbals, small 



watches, etc., in neat designs for the watch chain or waistcoat pocket, in gold, 

 silver, gilt, etc., inch and upwards, from . 2s. 6d. to 2 2 



492. Damp Detectors, being a very easy and sensitive means of ascertaining the exact 



state of damp or dryness of sheets or clothes ; small size for the waistcoat 

 pocket, in morocco case ..... 5 6 



493. DAMP DETECTOES, with pendants . . . . 076 



494. DAMP DETECTOES, strongly gilt . . . . . 10 6 



CLINOMETERS AND BOX SEXTANTS. 



495- Clinometer, or Geological Compass, for ascertaining the dip or inclination of 

 strata, hills, etc., with index, showing the inclination in degrees and inches per 

 yard, in square mahogany box, 4| inch, by f inch, thick . 10 6 



496. CLINOMETER, OR GEOLOGICAL COMPASS, 3-inch. . . 076 



497. CLINOMETER, OR GEOLOGICAL COMPASS, smaller size . . 066 



495 to 497, if with best bar needles, 2s. each extra. 



The inclination scale upon these clinometers, gives the value of any angle, as follows : The 

 angle having been ascertained from the divided arc upon the instrument, refer to that degree 

 in the column marked Angle, and opposite, in another column, will be found the rise or fall in 

 any given measured distance ; thus, say the degree shown on the divided arc is 18, opposite to 

 this number on the scale is 3, this indicating one part rise or fall in three, one foot in three, etc. 



