MECHANICS AND USEFUL ARTS. 91 



ployed by the Commissioners of Irish Lights. Further experi- 

 ments were also made, and it appeared that the whole of the gas- 

 lighting apparatus was entirely under the control of the keeper, 

 and that no damage was likely to arise from it. The 28-jet gas- 

 burner, when seen from a position some miles off, appeared to be 

 very nearly upon an equality with the oil lamps, but when muffled 

 to represent a fog it had a slight advantage. Of course with the 

 brighter jet-burners a great improvement was apparent, and be- 

 fore the 108-jet-burner the oil lamp grew quite pale. By the 

 adoption of a system of gas-lighting a great saving in cost would 

 be effected ; but such a system would not be possible on rock 

 light-houses. Professor Tyndall recommends the encouragement 

 of this system of illumination in Ireland. He was assisted in his 

 investigations by Mr. Valentin, Captain Roberts, and Mr. Wig- 

 ham. — Brit. Trade Journal. 



DISPOSITION OF GAS-BURNERS. 



Much of the economy and effect of gaslight, says the " Gaslight 

 Journal," depends upon the arrangement of gas-burners in rela- 

 tion to each other, to the surroundings of furniture, height of ceil- 

 ings, distance, and angles of walls, hangings, etc. 



The general practice in this country and in Europe, of dispos- 

 ing burners in chandeliers in the centre of rooms, althouefh 

 pleasing to the eye in its artistic effect, simply as an ornament to 

 the room, is far from being the most philosophical manner to 

 obtain the best effect from the light. 



The diffusion of light, in its effects, is materially modified by the 

 laws of reflection and refraction. 



Light decreases in intensity in proportion to the square of the 

 distance from the burner or point of illumination. This is a gen- 

 eral rule ; but in a room with four white walls and a ceiling, the 

 reflection of the light upon itself, as it were, will apparently mod- 

 ify the rule. 



Shadows have much to do in the effective and satisfactorj^ light- 

 ing of any hall or room. Hence it is that a single light, or a cen- 

 tre-piece, or nucleus of lights as represented by a chandelier, is 

 objectionable, because your shadow will appear in any part of 

 the room opposite to the light, and is more or less inconvenient 

 in" proportion as it differs in that resi)ect from daylight, which is 

 so diffused as to avoid this evil except in peculiar conditions. 



Now, in view of these suggestions, is it not apparent that the 

 proper and most eflicient position for gas-burners is at the difler- 

 ent sides, or, better, the different angles of a room ? Then the 

 intensity of light will be more uniform in every part of the room, 

 no shadows will be formed, and the reflective action of the walls 

 will be most effective. These reflections will show the folly of 

 usingbracket-lightsatonesideonlyof aroom, where shadows fall in 

 every direction it is possible to move from it, and with increased 

 intensity as you go, until the gloom of the opposite side brings 

 you back like a moth, to be blinded by the glare of the immediate 



