i ' Progress in Science. [January, 
conclusion of the course. Les Mondes also states that the same Dr. Poggioli 
Las succeeded in proving that electricity may be usefully employed as a sedative 
in nervous affections and certain acute forms of disease. 
Technology. — In consequence of the low pressure of gas during the day- 
time, trouble is often experienced from the retreating Bunsen burners of the 
usual construction. Th s having repeatedly proved a source of annoyance and 
loss, President Henry Morton, of the Stevens Institute of Technology, was led 
to the following consideration of the subject : — The retreat of a burner will 
evidently occur whenever any part of the ascending column of mixed gas and 
air is moving at the orifice with a velocity less than that at which the same 
will burn downwards. In an ordinary burner, with its main tube of regular 
cylindrical bore, it is evident that the friction of the surface of the ascending 
column of mixed gases will cause that portion to move at a less velocity than 
the central part, and that currents of the nature of eddies will be developed. 
Tt will thus happen that while the central portion of the ascending column of 
gaseous mixture issues at a velocity much greater than that at which the 
Material can burn downwards, and thus is quite free from any danger of re- 
treating, the marginal portions of the column or jet of gas will be escaping at 
a rate so much less that the velocity of their combustion downwards will 
exceed that of their upward motion, and retreat of the flame will ensue. It is 
well known that to secure a jet of water, or of any other fluid whose particles 
shall move with equal velocities in all parts, and thus avoid currents and 
eddies, it is only necessary to make the orifice of efflux an aperture in a thin 
wall. Following out the idea above indicated, President Morton made a burner 
of a bore rather large compared with its height, and then drew in its upper 
edge into the form of an open-ended thimble, so contracting the orifice of 
escape to about two-thirds the area of the tube, and rendering this orifice 
practically an opening in a thin horizontal wall or plate. The results of this 
modification far surpassed his anticipations. A burner thus constructed gives 
a perfectly non-luminous flame with gas pressures varying between 1-5 ando'i 
inch of water, and with the lowest of these pressures cannot be made to retreat 
by the most violent handling in the way of sudden movement or waving about 
in the air, even when this violence is carried to the extent of extinguishing the 
flame altogether. Under hke conditions of pressure, a burner of the ordinary 
construction is made to retreat by a slight draught of air, or a very moderate 
amount of motion. 
