I found two recently that need to be shared. The first one looks like a manufacturer of fire hoses. Sphincter grip galvanized armored spring steel hoses, to be precise, so you can trust them not to leak.
The other is a little more obscure. The advertiser is a John Matthews, who looks to be a long-time businessman in NYC. But the gold ink image in the center is quite unusual. This is a medallion engraving, created with something called a ruling machine, which drew a series of tight, parallel lines across a sculpted cameo to mimic a 3-D appearance. The results are similar to a topo map. This was an anti-counterfeiting device used mainly on banknote vignettes, but you can also find examples on the first U.S. newspaper stamps, PR1-3. This is the first example I've seen on a cover.
The subject matter is also intriguing. It looks like a cherub in a cape wielding a monkey wrench is fighting with a bear! I think a little research is in order here.
Addendum: It didn't take much Googling! By the 1870s, John Matthews was the premier soda fountain manufacturer in NYC. And I believe that bear is trying to drink out of an early fountain. https://www.boweryboyshistory.com/2...reating.html
And here is an updated version of the medal used to make the engraving:https://gwc-14060.kxcdn.com/wp-cont...500.jpg.webp