WE welcome the handbook entitled “Code for Protection against Lightning”, a revised edition of which has just been published (U.S. Government Printing Office, Washington, 1933, 15 cents). The number of fatalities from lightning in the United States is insignificant in comparison with the 100,000 annually from all other accidental causes. But the suddenness with which the flash happens, and the apparent impossibility of telling where it may strike next, may well frighten the bravest. Directions are therefore given for personal conduct during thunderstorms. If it is necessary to be out of doors, it is desirable to keep away from small sheds in exposed localities, isolated trees, wire fences, hilltops and wide open spaces. Shelter can be sought in a cave, a depression in the ground, a deep valley, at the foot of a steep or overhung cliff or in a grove of trees. Best of all is to stay indoors and keep away from fireplaces, stoves and all other large metal objects. Modern buildings are safe because of the protective effects of the metal used in constructing them and the metal piping on the exterior walls. The rules for erecting lightning conductors are now practically standardised. An approved protector should be placed as near as practicable to the point of entrance of an aerial telephone wire into a building. Metal radio masts should be bonded to the nearest lightning conductor. Wooden radio masts which extend six feet or so above the highest parts of the building should be provided with a connexion to earth. In an appendix, various kinds of lightning phenomena are described and modern theories are explained. A very instructive map is given showing the average number of days on which thunderstorms occur at many stations in the United States and Canada. There are very few thunderstorms on the Pacific Coast but at Tampa in Florida the number of days per annum on which thunderstorms occur is 94.