That's a carrier transposition bracket, used for high-frequency phone lines. The bracket allowed the lines to cross in an X pattern to avoid the "cross-talk" and other interference that can happen when phone wires are parallel to each other. It's not terribly valuable, maybe five dollars or so...
I don't think it's a dead end spool. The photo that Brutalfly posted doesn't show any sort of wire groove, and it doesn't match the pattern of any known dead end spool. The spools are well documented in the porcelain company catalogs.
A Hemingray-19 with round drips turns up in various tints of green, aqua, ice blue. None of them are particularly valuable in collector terms.
The 145.2 is a recent re-assignment and was a 145 for many years, usually called a pointed dome Star if someone wanted to distinguish it.
Not a bad find for taking a walk. Hemingray 42s are very common, but no reason you can't enjoy the nice fizz, bubbles, swirls, etc. that turn up in them. The aqua ones are from the 1920s. The "stick" is known as a pin.
What are the dimensions, and does the hole go all the way through? The first photo looks like it may have a solid top.
If there are holes at both ends, it could well be a transformer bushing, but that's not a pattern I've seen before and typically they have more skirts closer together. I'll...
Lapp Insulator Co. in LeRoy, New York. It's an intertwined L and I (for Lapp Insulator) inside an oval. They're still in business today.
The gap in the oval and L in your first photo are a date code, indicating your insulator was produced in the 3rd quarter of 1924.
Just based on the glaze color, this is pre-WW2. I can see a cemented joint, so it's definitely a two-part multipiece. It's tough to identify it exactly, but when it was whole it probably looked something like this catalog drawing.
It's not unusual to see Hemingray 42s and other communications insulators end up on low-voltage power lines, probably because of re-purposing. Back when this was common practice, there was no OSHA or ANSI so line builders just made do with what they had. Often that kind of line construction...
Interesting finds. The tall chocolate brown one is Illinois Electric Porcelain Co., with the logo in the shape of the state of Illinois. They were in business until the 1950s and that chocolate brown color indicates it's probably from the late 40s or early 50s.
The small pony is a telephone...
Nice find! It's definitely worth looking around there to see if you could find more.
For those wondering what the whole insulator looks like, here's a photo link:
The insulator would have been in a hole in the crossarm, with the metal hook...