I found these two insulators a while ago and I would like some information. The aqua insulator reads AM. TEL. & TEL. Co. The clear insulator reads Whitall Tatum No. 3 on the front and Made In U.S.A 26-42 on the back.
Not sure what information you're looking for, but here's a stab:
Your Whitall Tatum 3 is a telephone exchange. I think in addition to the embossing you give, there's an A in a circle on the back, indicating it was made by Armstrong after they bought out Whitall Tatum. The 28-42, if there are no dots added, indicates that it's mold # 28, made in 1942. These were commonly used on local phone lines.
The Am Tel & Tel is called a "toll" and these were used on both local and long distance telephone lines by (no surprise) Bell Telephone. Various glass companies produced these for AT&T beginning in the 1890s up through around 1920-ish. A few companies continued to make this style with the glass company name embossed on it up through the 30s, but I don't know offhand if Bell was the buyer for these or other telephone companies. I imagine probably both. Your example is probably from the late 1890s to 1920. They didn't change much from year to year so it's tough to be more precise than that. Does it have a letter or number on the dome top? If so, it was probably made by Brookfield.
Both of these were mass produced for a number of years so they don't have much collector value. If you're just interested in telephone history, you're well on your way to starting a nice little collection!
