Managemeiit of Light in Illumination. 119 



so that the form of the illuminator when lighted is 

 always simple and elegant. 



The lower hemispherical screen of the balloon illu- 

 minator is attached to the brass hoop by means of a 

 hinge, and it is fastened to the opposite side of it by 

 a hook ; but the upper hemispherical screen of all the 

 illuminators is merely laid down on the top of the 

 reservoir, and may be taken away whenever it is nec- 

 essary. 



These screens, notwithstanding that their openings 

 both above and below are circular, are not of a spheri- 

 cal form, though when seen at a little distance they 

 appear to be globular. They are composed of skele- 

 tons made of strong iron wire, wound round with nar- 

 row^ thin white silk ribbon, and covered with thick 

 white gauze or white crape. The wire is so disposed 

 as to form nine or twelve vertical ribs, according to the 

 size of the screen ; and, where ornament is required, 

 these ribs are covered on the outside, and entirely con- 

 cealed from the view, by rows of brilliants of cut glass, 

 gradually diminishing in size from what may be called 

 the equator of the balloon towards its two poles. 

 These brilliants, being perforated with small holes at 

 each of their extremities, are easily attached to the ribs 

 by screwing. 



By covering the whole of the surface of the balloon 

 in this manner with cut glass, a most beautiful and 

 splendid effect may be produced without sensibly 

 diminishing the light or disturbing the agreeable mild- 

 ness and tranquillity of the illumination. One balloon 

 illuminator has already been ornamented in this man- 

 ner under the direction of M. Ravrio, and has been 

 much admired. It was made to occupy the middle of 



