ALL PHOTOS ARE THERMOMETERS WE CURRENTLY HAVE AVAILABLE
Advertising thermometers were a popular item between the 1920's and 1960's, and were distributed by a great number of brands. Common vintage thermometers include the round ones resembling a clock face, with a hand pointing to the temperature, and the vertical rectangular or cigar-shaped thermometers with a mercury meter in the middle. Some advertising thermometers, such as those made by soda companies like Coca Cola, Pepsi, etc, often took the shape of a bottle.
These were usually given away to store owners to advertise the merchandise they handled.
Then there are those that were made for your Mom and Pop stores and given free to their customers to remind them where to go to do business in the future. A traveling salesman would visit storefronts showing examples of advertising options in thermometers economically. Plus there were those made for the general public to purchase minus a specific brand advertisement, but why buy one when your neighborhood hardware store etc, would give you one free if you frequented often enough.