RANELAGH CLUB 



6487 



RANGE-FINDER 



Ranelagh Club. London social 

 and sporting club. Established in 

 1894, in Barn Elms Park, S.W., it 

 provides facilities for polo, golf. 



A simple instrument of this type 

 was the mekometer (length mea- 

 surer), used by British infantry, 

 consisting of two reflectors joined 

 together by a cord 

 25 or 50 yards 

 long. One observer 

 was at each 

 instrument, these 

 being so arranged 

 that the one 

 showed when the 

 base made a right 

 angle with the 

 imaginary line to 



* the target, and 

 The Club-house from the Bounds tfae oth r could 



croquet, tennis, etc. Attached to then be sighted on the same object 

 the club-house is a building once by adjusting a knob which carried 



a pointer moving over a dial 

 graduated direct in yards instead 

 of angles. 



The vastly increased power of 

 modern artillery, making it possible 

 for guns to fire accurately to 

 ranges of 20,000 yards, has natur- 



Ranelagh Club. 



known as Queen Elizabeth's Dairy. 

 Here Jacob Tonson, founder of the 

 Kit-Cat Club (q.v.), died in 1735. 

 (See Barnes.) 



The name Ranelagh is given in 

 Paris to a grass plot and avenue 

 near to the Porte de la Muette, 

 once the site of a club founded in 

 1774, and notable for its fetes. 



Range (O. Fr. rent,, rank). 

 Word employed in various senses. 

 1. Primarily a series of things in 

 a line, a continuous chain, e.g. a 

 range of mountains. 2. In gunnery 

 it is the horizontal distance to 

 which a projectile can be thrown; 

 and also the place where rifle or 

 artillery practice is carried on. (See 

 Range-finder ; Rifle Range. ) 3. 

 In music, range is the compass of a 

 voice or instrument. 4. The limits, 

 geographical, or in point of time, 

 within which an animal or plant is 

 distributed, or has existed, on the 

 globe. 5. A cooking stove built into 

 a fireplace is known as a kitchen 

 range. It is closed with iron plates 

 and has one or more rows of open- 

 ings on the top for carrying on 

 several cooking operations at once. 

 Fixed ranges may have one or two 

 ovens. A boiler fitted at the back 

 of the fireplace may supply hot 

 water, and a tank, included with 

 the boiler in a hot water circulat- 

 ing system, may provide water 

 for domestic use. Modern ranges 

 are usually portable. \ 



Range-finder. Instrument 

 used to ascertain the distance of 

 the target from the firing point. 

 Various types have been evolved 

 to meet the different conditions ex- 

 perienced in warfare. The majority 

 depend on the principle of mea- 

 suring the angles of the triangle 

 which is formed by making the tar- 

 get the apex and the instrument 

 the base ; and in order to simplify 

 the measurements to be taken it is 

 usual to arrange that one of the 

 base angles is a right angle, leaving 

 only one unknown angle to measure. 

 The instrument is thus actually a 

 goniometer (angle measure). 



Range. 



Kitchen range with transparent oven door 

 and many conveniences 



By courtesy of Eagle Range A Orate Co. 



ally demanded equivalent progress 

 in the science of range-finding, and 

 the instruments made by Barr and 

 Stroud, and supplied to the 

 British services, are outstanding 

 examples of modern practice. In 

 principle, these are also depen- 

 dent on measuring the angles 

 which two beams of light from the 

 target make with the opposite ends 

 of a known base line, and the latter 

 is formed by a rigid metal tube 

 having pentagonal reflecting 



prisms fixed in each end. These 

 prisms divert the beams of light 

 along the axis of the tube, and 

 through objective lenses also fixed 

 near each end. At the centre of 

 the tube other prisms divert the 

 beams into a single eyepiece, and 

 are so arranged that the beam of 

 light from the right end forms the 

 upper, and that from the left the 

 lower, half of the field. It is 

 thus obvious that the angles of the 

 prisms must be varied to enable 

 a continuous complete image to be 

 obtained of targets at varying 

 distances from the base. 



In practice, especially at long 

 ranges, if the base is made of any 

 convenient length, the angular 

 variations required of the prisms 

 are so small that sufficiently accur- 

 ate mechanical movement could 

 not be arranged, and, further, the 

 scale would be too fine to be read. 

 These difficulties are obviated by 

 interposing between one of the 

 object glasses and 

 the eyepiece a 

 deflecting prism of 

 small angularity, 

 and definitely fix- 

 ing the penta- 

 gonal prisms in 

 the ends of the 

 tube. By mov- 

 ing the deflecting 

 prism along the 

 optical axis the 

 beam of light is 

 diverted as if the 

 angularity of the 

 pentagonal prism 

 were altered, but 

 as the necessary 

 lateral motion 

 of the deflecting 

 prism is oon- 

 siderable, an open 

 and easily read 

 scale can be pro- 

 v i d e d, and the 

 accuracy required 



of the mechanical adjustment can 

 be attained. 



Suitable lenses are also provided 

 for use when required, which 

 distort a small object, such as a 

 single light, into a vertical line, thus 

 rendering it easy to see when the 

 two half images coincide, and an 

 optical system is also provided for 

 checking the accuracy of the 

 readings. The greater the length 

 of the base, the more accurate are 

 the determinations, especially at 

 long ranges, and 



Right Reflector 

 Deflecting Prism \ 



Right Objective 



Left Objective / 



Central Kef lectors I 

 Range-finder. Diagram illustrating principles on which 

 the Barr and Stroud instruments are constructed 



for naval and 

 fortress use the 

 instruments have 

 a length between 

 the pentagonal 

 prisms of 9 to 35 

 feet, while port- 

 able range-finders 



