3^0 Dtscription of Ramage*s 



use of a thin chimney-pot, whose inside 

 is so mncii cooled by the snrrouiuling 

 air and cold wind, is tlie canse of many 

 a chimney's smoking: and that the 

 sheet-iron funnels, often erected as a 

 mode of cure, are from this cause ineffi- 

 cient, unless raised inordinately high. 

 Towards confrrming; or confuting this 

 last opinion, I wish that comparative 

 experiments should at the same time he 

 made, of the actual heat in the tops of 

 iron funnels, in those of chimney-pots, 

 and in the tops of brick chimneys, having 

 no more than a sufficient extent of open- 

 ing, and provided with a properly 

 formed copcing, like that shown by Mr. 

 Tredgold in p. 91. The subject is one 

 of great importance to domestic com- 

 fort; and will, I hope, attract the 

 notice of the proper persons to give it 

 an experimental elucidation. 



O. H. 



For the Monlldy Magazine. 



ramage's reflecting telescope. 



(With an Engraving.) 



WE have this month given an en- 

 graving of one of the reflecting 

 telescopes made by Mr. John Ramage, 

 of Aberdeen. The readers of the " Mo- 

 dern Voyages and Travels," will recol- 

 lect a short notice of it in the third num- 

 ber from ]\I. Dupin and Dr. Gregory, 

 who were much delighted with the ex- 

 cellence of the instruments, their facility 

 of use, and valuable observations of the 

 heavens, worthy of an observatory of the 

 first order. They were astonished to 

 find such inventive talents and know- 

 ledge in an humble currier, who devotes 

 the leisure hours spared from his busi- 

 ness to scientific pursuits, whose know- 

 ledge and genius are only excelled by 

 his great modesty and readiness to 

 oblige. The drawing, and the following 

 short description, were furnished by a 

 correspondent who visited Aberdeen last 

 autumn. 



The telescope, of which the accompa- 

 nying sketch was taken, is placed at 

 Broadford, near Aberdeen, in the 

 grounds of Dr. Dauney, the professor 

 of law. The tube is twenty-five feet 

 long, and its diameter eighteen inches. 

 At the bottom of the tube, when the tele- 

 scope is to be used, is placed a metallic 

 speculum, finely polished, of fifteen 

 inches diameter. From this speculum, 

 a fine bright, and clearly defined image 

 of the body observed, is reflected; and, 

 as an eye-piece of only a small magnify- 

 ing power is required, there is as plea- 



Reflecting Telescope. [June 1, 



sant and distinct a view as tf the object 

 were seen by the naked eye. The supe- 

 rior view of the heavens, as seen by such 

 an instrument, can be appreciated by 

 those only who have enjoyed the ad- 

 vantage of an observation with it. To 

 produce any considerable power npon a 

 small telescope, deep magnifying eye- 

 glasses must be used ; consequently, the 

 field of view is much contracted, and, 

 there being but little light, the object is 

 seen very nnsaiisfaclorily. But, with 

 the large reflecting telescope, the obser- 

 vation is one continued source of un- 

 mixed pleasure. Mr. Ramage's tele- 

 scope is creeled on a cast-iron platform, 

 274 feet in diameter, on piles jointed 

 and dovetailed together. The whole 

 was placed in a horizontal position by 

 means of a spirit level. The centre part 

 is sunk four feet deep. The telescope is 

 moved round to any direction on cast- 

 iron rollers, by a winch at the end, near 

 the lower part of the lidje, and a rope. 

 The tube of the telescope is raised to any 

 altitude by the winch represented in 

 front of the drawing. When it is de- 

 sired to direct it to the zenith, or to any 

 high elevation, the end of tlie tube is 

 brought forward. The gallery on 

 which the observer stands is elevated 

 by a simil.ar winch on the opposite 

 side. All the motions of the telescope 

 are produced in the simplest manner by 

 means of a few cords: yet the telescope 

 is perfectly steady and free from tremor, 

 and may be managed by the observer 

 without an assistant, almost as easily as 

 a three-feet achromatic telescope. This 

 is a decided advantage, as the observer 

 can place the tube in the most favourable 

 position for vision better than any as- 

 sistant. When the observer is in the 

 gallery, he is able to keep the object a 

 long time in view, as the telescope may 

 sweep backwards and forwards 10°, and 

 the observer may elevate or depress it, 

 and himself, with one hand. The ma- 

 chinery of Herschel's twenty-feet tele- 

 scope is very complicated, and requires 

 two assistants. 



Mr. Ramage is now engaged in pre- 

 paring a grand telescope, of which the 

 speculum is fifty-four feet focal length, 

 and twenty-one inches diameter. The 

 casting and polishing of the specula, 

 and erection of the telescopes, are done 

 under his direction, and, in a great 

 degree, with his own hand. The excel- 

 lence and simplicity of management 

 alike entitle the instruments to ad- 

 miration. 



To 



