I am conducting a small research project and will appreciate the assistance of members of the Forum.
An entry in the Pritchard & Andrews proof book shows that, in February 1870, a proof strike was done of a solid crown device qhich was, apparently, destined for use in Ottawa.

According to an article written in volume 97 of the Postal History Society of Canada Journal, only 5 strikes from this device are known to exist and all are on government mail dated in mid March 1870.
I have discovered a piece of commercial mail (dated March 20, 1870) bearing this cancel but have a great deal of difficulty believing that others don't exist (unless the device was lost or broken.
There is a second Ottawa Crown but I don't know whether it is a replacement or just a second device but it was used for several years beginning in April 1880.

If any of our Forum readers has a cover bearing a strike of the solid crown cancel, I would truly appreciate receiving a scan of that item. The research on my item is the subject of an article that will appear in The Canadian Philatelist in an upcoming issue.
Thanks for any assistance that can be provided.
GJP