a7 
8. Holtz machine ‘‘ Brush” discharge (Photographic 
plate being placed horizontally between the elec- 
trodes), showing electric ‘* lines of force.” 
g. Holtzmachine spark (plate being placed vertically be- 
tween the electrodes), showing electric ‘‘ lines of 
foree:” 
10. Meandering discharge. Illustrating the service of trees 
during a thunder storm—to dissipate, neutralize or 
conduct the discharge. 
11. ** Beaded” or ‘* Rosary” lightning. Supposed to be 
the track of a rotating ball of fire moving through 
space. A ‘* thunderbolt.” 
12. ** Beaded” or ** Rosary ” lightning. 
3. Two parallel discharges branching from a main stem. 
14. Radial lightning. The discharge having the appear- 
ance of heat-cracked glass. 
15. Collision of two discharges in mid-air, and the produc- 
tion of ** thunderbolts.” 
16. **Ribbon” lightning. (An oscillating discharge 
moved by the wind.) Caught on the prairie of 
North Dakota at midnight from the rear platform of 
an express train. 
15. REPRODUCTION OF THE THREE CoLor Process. Negatives 
and plates untouched by hand. Examples are from Life, 
Nature, Still Life, Paintings, produced by the N. Y. 
Photogravure Company. Exhibited by Ernest Edwards. 
16. RADIOGRAPHS WITH ‘‘ ROENTGEN” Rays, and other photo- 
graphs. Exhibited by John S. McKay. 
1. Photographs of Apparatus used in producing Réntgen 
rays. . 
2. Radiographs of hand containing bullet. Frog with 
broken leg. Bird with shot in body. 
3- Radiographs showing skeletons of small animals. 
Frog, turtle, salamander, etc. 
4. Radiographs showing relative capacity to ‘‘ Réntgen 
rays” of various solids and liquids. 
