What was the purpose of the “bathing machine”? Looks like a little portable changeroom?
Yes, they were for changing in.
Here’s the article that uses that pic : Bathing Machine. Apparently they were not only a changeroom, but also carried people into the water, as well as hiding the bathers from view of the shore.
Plimoth Plantation is near modern Plymouth MA. The period is Circa 1627.
Old Sturbridge Village is not too far away in Sturbridge MA. 1790’s to 1830’s.
Here’s a famous portrait of Madame Récamier relaxing. This must be what downtime looked like for the upper class in the year 1800 (unless she’s dressed a little fancier to sit for a portrait).
I don’t know if the clothing styles go back 200 years, but one of the most interesting things about traveling in the smaller towns and cities in India is how many of the locals wear “Indian” clothes.
Outside of Mumbai and Delhi, virtually all the women you see are dressed “local” and this is true for most of the men. In some places, when you couple the Indian architecture with the people one sees, you’d swear you were on a movie set for “Indiana Jones”. And this is not some special Festival Day. Its just everyday life in India.
I once got on a bus in a small town in the south and every man (and boy) was dressed in identical clothes, even the driver. It was a white hat with a bill and white loose fitting shirts and pants, but they were all cut and styled the same.
Just so - a man’s shirt was underclothing, the equivalent of a modern undershirt. That’s the point of the scene in Pride And Prejudice when Elizabeth Bennett and her uncle and aunt unexpectly come across Mr. Darcy, fishing with his coat off - they’ve caught him in his undies. And just as modern men ofter sleep in their t-shirts and shorts, 18th cent. men often slept in their shirts.
Under his breechs or later his trousers, he wore a pair of linen or cotton “drawers”, rather like knee-length boxer shorts, usually made at home by his wife.
Hello! Guess it wasn’t cold at the beach that day. 
Cites?