Page:Popular Science Monthly Volume 92.djvu/192

 The Germans are Coming! Sound Bombs Soar

���Photos © Int. Film Scrv.

��When air raiders approacli London warning is now given by sound bombs which rise three hundred feet before ex- ploding. Above is shown the mortar which is used for firing the rockets. They get results

��Inserting the time fuse in a rocket before sending it aloft. The bombs produce a tre- mendous noise which can be heard over great areas. Lon- don has come to know this helpful "run to cover" signal

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