Once the direct vision ports were eliminated from Sherman hulls, we know that the driver and asst driver were equipped with a fixed, forward facing periscope housing and a rotating one in his overhead hatch. These were present for both the 47 and 53 degree glacis configurations.

In contemporary photos, the fixed ones are rarely in use. Indeed, I went through a few books and found maybe two or three pics per book where a periscope is in that fixed housing. For the hatch-mounted, rotating one, the periscope is present most of the time.

Why was the fixed one so unpopular? Was it simply extraneous since you were going to use the hatch-mounted, rotating one anyway? I get that for the 53 degree hulls, the front one would interfere with the line of sight for the rotating one -- but for the big hatch tanks, you could use both the rotating one and the fixed one. Just duplication of effort and another item that might get shot up?

I don't recall reading about any actual anecdotes about the fixed periscopes. Can anyone shed any light?

Thanks!

Just a thought Roy, the fixed periscope in the 47 degree hull was off center so the driver would have to lean over to use it. Rather difficult to do driving buttoned up. Its much easier to use the one right in front of you. Driving closed down is tough enough. Also the one in the hatch rotated so it was easier to look around. I was a tank driver for my time in the 11th ACR it takes some practice and you have to look straight ahead and anticipate the ground since you view is at least 15 to 20 feet out.

Another thought thought, the early Pershings had that extra periscope and it was removed on later production tanks. My guess it was considered redundant and also weakened the roof.

Tom

Soldiers are lazy. Rather than mounting and dismounting two periscopes to basically see the same thing, they just use one.

The way that requires the least effort will usually triumph over any other no matter what advantages the other may offer. It's human nature. Numerous psychological studies have pointed this out. Think of it as a kind of Occum's razor for physical activity. What requires the least effort will be perceived as the simplest and therefore will be preferred.

Additionally, when you have a periscope conveniently overhead, why would you ever use the completely redundant one in front of you?

And this explanation also fits the criteria for Occum's razor. It happens to be the simplest explanation and that is usually the correct one.