Progress of Invention. 311 



Peculiar Application of Electricity. — The brilliancy of the 

 electric spark very soon suggested it as a means for obtaining 

 artificial light, and numerous experiments were made with the 

 object of utilizing it in that way. These experiments, though not 

 altogether unsuccessful, led to no practical results. Among the 

 difficulties experienced in the application of machine electricity to 

 the purposes of illumination, one of the most serious was the im- 

 possibility of obtaining perfect insulation. This does not exist to 

 the same extent with galvanic electricity, and hence the application 

 of this form of electricity to illuminating purposes has been attended 

 with better success ; and the improved modes of producing it, and 

 other forms of that agent having a controllable intensity, has given 

 an impetus to the efforts of those who count on the application of 

 the electric light to practical purposes. One of the most curious 

 instances of this application is, perhaps, that recently made in Paris 

 for the production of theatrical effect. Light metallic crowns, 

 having slight interruptions, were worn by some of the performers ; 

 and when the galvanic current from a concealed battery was trans- 

 mitted through these crowns, brilliant stars of light were produced 

 at the interruptions. The most costly diamonds would not have 

 afforded an equally brilliant effect. The danger of so powerful an 

 agent as a strong galvanic current in the hands of the inexperienced 

 or the neglectful, was illustrated, at the same time, by the fact that 

 one of the performers was seriously injured, the head having been 

 allowed to form a part of the circuit. 



Sonorous Vibrations, a Means of Measuring Minute Portions 

 OF Time. — An apparatus recently perfected by M. Niaudet-Breguet 

 affords a simple means of measuring, with ease, extremely 

 minute portions of time. In its earlier forms, this apparatus was 

 employed only to record graphically the vibrations of sonorous 

 bodies. It originally consisted of a tuning fork, on one branch of 

 which was fixed a point, that, when the fork was set in vibration, 

 described a sinuous line on a cylinder covered with lamp black, 

 and made to revolve by clock work. To render the vibrations con- 

 tinuous, instead of lasting but a very short time, each branch of the 

 tuning fork was alternately attracted by an electro-magnet, which 

 was placed very near it, and which was, at suitable intervals, placed 

 in connection with a galvanic battery, by means of the apparatus 

 usually employed for making and breaking connection with the 

 ordinary induction coil. The apparatus was so arranged that the 

 sound produced by the apparatus for making and breaking contact 

 was in unison with, or some octave of that of the tuning fork j which 

 was effected by turning the regulating screw. 



The next improvement introduced into the apparatus, was the 

 substitution of one of the branches of a tuning fork," having a pitch 

 corresponding to the tuning fork attached to the apparatus for 

 graphic delineations, instead of the vibrating metallic slip, used with 

 tiie induction coil. 



M. Niaudet-Breguet's improvement consists in the use of an 

 horological instrument, in which the pendulum is replaced by a 

 tuning fork ; the movement of the wheel work being controlled by 



