III. SURVEYING. 763 



This instrument, when folded up, measures 3 inches square by 2^ inches 

 deep, and weighs 2 Ibs. 2 ounces. 



It contains within a box, hinged together in three parts, twenty instruments, 

 as follows : Anemometer, aneroid barometer, clinometer, goniometer, ther- 

 mometer, circumferentcr, protractor dial, prismatic compass, hypo-thonite, 

 quadrant, spirit level, limb and sights for taking altitudes, sun-dial, callipers, 

 plummet, magnafying lens, Nicol prism, scale of inches, scale of chains ; 

 added to which are arranged two tables of constants and useful formulae, and 

 an easy method of ascertaining the variation of the magnetic needle. 



It is a measurer of time, heat, velocity, and pressure, also of height, depth, 

 length, and breadth ; and of horizontal, vertical, acute, and oblique angles. 



It is made so portable in form and weight as to enable it to be carried in 

 the pocket, and yet it possesses sufficient size and strength to render it a 

 trustworthy and useful companion to military, civil, and mining engineers, 

 geologists, mineralogists, railway and land surveyors, and travellers. 



31O3. Drawing of a Horizontal Goniometer for deter- 

 mining geographical longitude without a chronometer. 



H. Haedicke, Demmin, Pomerania. 



The instrument of which this is a drawing serves, in the first place, to 

 determine by direct reading the angle formed by the line joining two stars 

 (a i) with the horizon. The handling of the instrument is for this purpose 

 similar to that of the sextant ; that is to say, the moment must be noted when 

 the star line is covered by the hair line of the instrument. That an observa- 

 tion may be carried out on board ship, the instrument is provided with an 

 arrangement which enables the position of the scale with respect to the 

 artificial horizon to be fixed at the moment of the observation, so that the 

 angle can afterwards be read by means of a vernier. 



AVhen in this manner the angle of a second star line (c c?) to the horizon 

 has been determined, a simple subtraction will give the angle between the 

 star lines a b and c d. Should there be a planet among the stars a, 6, c, d, 

 it becomes possible, by means of a proper astronomical table, to calculate 

 the astronomical time as well as (if the local time be known) the geogra- 

 phical longitude of the place of observation. 



3127. Instrument, called Metrostroph, for the Con- 

 struction of Altitude Curves (contours). 



Bau Deputation, Hamburg. 



This instrument is a variable scale, invented by F. H. Reitz, which facili- 

 tates plotting apoint on a contour line from the two nearest points, the levels 

 of which are determined. See 3217a. 



3151. Two Levels, sensitive to show one second of inclina- 

 tion by -^ of an inch in any part of their length. Adam Hilger. 



These levels were made at the desire of the late Colonel Strange, F.K.S., 

 to stand a hot climate like India, and ckn be easily filled with ether. 



The glass tubes are 9^ ins. long by f ins. in diameter and ground to a 

 radius of 1,000 feet. The ends. of the tube have glass plates, which are 

 spherically ground and very highly polished, and fit so accurately that no 

 ether can escape, the ends being kept in their places by a spring which has 

 three arms. The ends of the brass -mounts have bayonet joints, so that the 

 level can easily be refilled. 



