I ran across some articles recently describing a pneumatic mail delivery service between PO's in Manhattan and Brooklyn from the 1900's. I was wondering if anyone knows if the PO affixed any type of special cancel to stamps when they were cancelled and were transferred between PO's using this method. I did not find any mention of any being used when I read thru these articles and others that I found on web. The US did not issue any special pneumatic mail stamps that I am aware of. I believe there were no special cancels or markings used as the practice seems from the articles to be the normal way of getting mail around the city prior to the use of trucks later on.
Would appreciate any additional info that someone may be aware of.
Thanks for your post and link. I do not think it was off-topic as it concerns how differnet PO areas marked their pneumatic mail. I have yet to see any with markings from NYC so I believe that they did not use any but as your post shows, the Chicago area did. I quess the absence of markings would make collecting NYC covers difficult if not impossible as you will never be able to positively determine if it weny thru the pneumatic mail system. You could assume that special delivery covers during the time period did, but that would only be a guess without the markings.
