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MGI VOL 2124 number 306 [handwritten in pencil, top right]

HALIFAX DISASTER RECORD OFFICE
CHRONICLE BUILDING

HALIFAX, N. S.

[Newspaper Clipping]
[Column 1]
A [handwritten in blue ink, next to the title]
SCIENTIFIC MEN INQUIRING INTO THE HALIFAX EXPLOSION.
National Geographic Society at Washington, D. C., In Correspondence with Truro Members.
A Circular Letter from the Editor of the National Geographic Magazine, the organ of The National Geographic Society, Washington, D. C., has been sent to the Truro members of this Society, making inquiries in regard to "The Halifax Explosion," and asking for certain information or data, bearing upon this disaster, that may be useful in the studies coverd by such a Society.
The following is the Circular referd to:-
THE HALIFAX EXPLOSION.
"As the explosion which occurred at Halifax, Nova Scotia, on December 6th, 1917, was one of unusual magnitude and the amount of explosives involved was very large, it is believed that this unfortunate disaster affords an especially good opportunity to secure data as to the distance the explosion and sound waves travelled, their velocities, and the areas in which the sound was heard.
"An interesting result of recent invetsigation is the recognition of the fact that there exists sometimes, though not always, a
ZONE OF SILENCE
which separate two detached sound-areas. This zone has been traced in twenty recent explosions, two being due to gun firing, four to explosion of gunpowder or dynamite and the remainder to volcanic explosions.
"It will be of value to ascertain whether the Halifax sound-area belongs
[Column 2]
to the single or double group.
"To secure the date the Editor requests that persons living within 250 miles of Halifax at the time of the explosion and who were in a position to make an observation at the time of the accident,
INFORM HIM
whether or not they hear the report, and if they did, how many successive reports, giving the time they heard each as accurately as possible, and naming the place they were in at the time so that it may be identified on the map.
"Doctor Alexander Graham Bell reports having heard the explosion at Baddeck, Cape Breton, nearly
200 MILES
distant. It is possible that observers at more distant points may have heard the report or noticed its effects in shaking buildings and their contents, while others nearer to Halifax, who were awake, alert, and in a position to observe, neither heard a report nor observed any effect on the surrounding structures."
Dr. J. B. Calkin, Truro, is in communication with the Editor of this Geographic Magazine, Gilbert H. Grosvenor, and he will gladly send to him any information that our towns people, or others, may give him relativ to the effects of this explosion.

PUBLIC ARCHIVES OF NOVA SCOTIA HALIFAX [circular stamp, blue ink, located below the Newspaper Clipping by the bottom right]