The most important thing to know when searching for a patent of invention at Library and Archives Canada (LAC) is the date range when the application was filed. Following are some search options and strategies for each time period.
Pre-1869
The original patents of invention series includes applications that originated in present-day Ontario and Quebec dating back as far as 1824. Two publications, the Index of Inventors and Inventions for Canadian Patents, 1824–1872 and the List of Canadian Patents, from the Beginning of the Patent Office, June, 1824, to the 31st of August, 1872 serve as the finding aids for this series. LAC also holds pre-Confederation patent applications that were filed in Nova Scotia, New Brunswick and Newfoundland. These documents are individually described in finding aids that can be consulted onsite in Ottawa or via Reference Services.
1869–1919
The Canadian Patents, 1869–1919 database is searchable by patent title keyword, inventor or year filed. For example, the patent application for a hockey goal can be found by searching with the keyword “hockey.” The associated digitized documentation includes one drawing.

Drawing of hockey goal, 1911 (patent number 139387)
These documents are held by LAC in the accession Canadian Patents, 1869–1919. Consultation of the originals is limited for conservation reasons and each request will be reviewed by custodial archivists.
Post-1919
Although the Patent Branch series of the Canadian Intellectual Property Office fonds is the best place to find these patents at LAC, you can consult the Canadian Patent Database on the Canadian Intellectual Property Office (CIPO) website first as it provides not only basic information about specific patents, but also digitized versions of the applications.
For example, in researching the Moir family’s chocolate business, you can discover that William A. Moir patented a chocolate machine in 1927 that was described by Moir as being “particularly useful in the candy making art.” Sixteen pages of associated documentation including drawings, one of which is shown here, are all available online for immediate consultation. Complete references necessary for ordering the originals for consultation at LAC can be found in finding aid 105-8.

Drawings for William A. Moir’s chocolate machine, 1927 (Canadian patent document number 267441)
Best of luck with your research endeavours—and don’t hesitate to contact Reference Services if you have any questions related to searching for patent applications, or other archival documents held at Library and Archives Canada.
Pingback: Vol. 9, no. 25 | I-Heritage.info