364 On the Ventilation of Lighthouse Lamps. [1843. 



The ventilating pipe or chimney is a copper tube, 4 inches in 

 diameter, not, however, in one length, but divided into three 

 or four pieces : the lower end of each of these pieces, for about 

 1^ inch, is opened out into a conical form about 5^ inches in 

 diameter at the lowest part. When the chimney is put together, 

 the upper end of the bottom piece is inserted about an inch 

 into the cone of the next piece above, and fixed there by three 

 ties or pins, so that the two pieces are firmly held together ; but 

 there is still plenty of air- way, from the surrounding atmosphere 

 into the chimney between them. The same arrangement holds 

 good with each succeeding piece. When the ventilating chimney 

 is fixed in its place, it is adjusted, so that the lamp-chimney 

 enters about \ an inch into the lower cone, and the top of the 

 ventilating chimney enters into the cowl or head of the lantern. 



With this arrangement, it is found that the action of the 

 ventilating flue is to carry up every portion of the products of 

 combustion into the cowl ; none passes out of the flue into the 

 air of the lantern by the cone apertures, but a portion of the 

 air passes from the lantern by these into the flue, and so the 

 lantern itself is in some degree ventilated. 



The important use of these cone apertures is, that when a 

 sudden gust, or eddy of wind, strikes into the cowl of the lantern, 

 it does not have any effect in disturbing or altering the flame. 

 It is found that the wind may blow suddenly in at the cowl, yet 

 the effect never reach the lamp. The upper, or the second, 

 or the third, or even the fourth portion of the ventilating flue 

 might be entirely closed, yet without altering the flame. The 

 cone junctions in no way interfere with the tube in carrying up 

 all the products of combustion; but if any downward current 

 occurs, they dispose of the whole of it into the room, without 

 ever affecting the flame. The ventilating flue is, in fact, a tube 

 which, as regards the lamp, can carry everything up, but 

 conveys nothing down. 



In lighthouses with many separate lamps and reflectors, the 

 case is more difficult and the arrangement more complicated, 

 yet the conditions before referred to are more imperatively 

 called for, because any departure from them was found to have 

 greater influence in producing harm. The object has been 

 attained thus: A system of gathering pipes has been applied 

 to the lamps which may be considered as having the different 



