B. TERRESTRIAL PHYSICS AND METEOROLOGY. 117 



FIGURES MADE BY LIGHTNING. 



Professor Tomlinson, in writing on the subject of the fig- 

 ures or marks left on the bodies of men or animals killed by- 

 strokes of lightning, states that very instructive tree-like 

 figures may be produced on sheets of ground glass by pass- 

 ing over them the contents of a Leyden-jar. These figures, 

 like those on the human subject, are not derived from any 

 tree whatever, but represent the path of the lightning itself. 

 This subject has been studied by numerous authors ; among 

 others by Poey, who, in 1861, published a small volume, in 

 which twenty-four illustrative cases are cited. He accounts 

 for their formation as a photo-electric effect, in which the 

 surface of the animal is the sensitive plate, the tree, etc., the 

 object, and the lightning the force that impresses it. Among 

 many remarkable cases that can be quoted was one that oc- 

 curred at Zante, where the mast of a vessel was struck, and 

 a sailor sleeping in a cot on the deck was killed. The num- 

 ber 44, in metal, was attached to the fixed rigging between 

 the mast and the cot. On the left breast of the dead sailor 

 was found the number 44 well formed, and perfectly identi- 

 cal with that on the rigging. Light was thrown upon these 

 cases by Mr. Varley, who, noticing some specks on the me- 

 tallic ball of the positive pole of a Holtz electric machine, 

 tried to wipe them off with a silk handkerchief, but in vain. 

 He then examined the negative pole, and discovered a mi- 

 nute speck corresponding to the spots on the positive pole. 

 It was evident that lines of force existed between the two 

 poles, by means of which, as it were, telegraphic communi- 

 cation was made from one to the other; and in explanation 

 of the marks made on the human subject, it is stated that a 

 lightning burn on the skin is produced whenever the object 

 struck is electrically positive to the metallic object, the dis- 

 charge itself being a negative one. 



CLIMATOLOGY OF FLORIDA. 



In an address on the climatology of Florida, recently de- 

 livered by Dr. Baldwin, the author gives some interesting 

 statistics, whose value is indicated by the fact that they are 

 based upon thirty -six years' meteorological observations, 

 recorded by himself, at Jacksonville, together with numerous 



