On the same page, it is even more interesting to see the mentions of personal information about plumbers, such as the birth of a baby boy and this great photo of a plumber and his wife!
"We show in the present issue a portrait of that successful master plumber of 90 Lowry street, Troy Hill, Allegheny, Pa., John B. Heid, and his charming wife. Mr. Heid is just installing a nice piece of plumbing in the Hubert residence on Troy Hill, and is known far and wide for the high quality of his work. He has one of the best shops in Allegheny and has performed some of the best contracts in that neck of the woods. He has a very delightful home on Lowry street, a couple of squares from his shop. Mr. Heid looks forward to a good year in 1906 and judging from his record in the past he should have a big number of contracts on hand by spring. Mr. and Mrs. Heid recently returned from their wedding trip, which included Cleveland, Buffalo, Niagara Falls, New York and Boston."
Trade journals can tell you more about an ancestor than items related to his profession. You may get lucky and find some great personal details.