We don't collect subsurface observations (oceanographic data), but there are people who do
. One of the earliest projects in environmental data archaeology was GODAR
which aimed to recover exactly this sort of measurement. So if you find any actual temperatures please let us know.
My guess is that the 'machine' is some sort of Nansen Bottle
- there's a whole alphabet soup of gadgets for measuring temperature at depth (see here
), but most of them were not around in our period (nowadays the job is done by robots
The Nansen bottle was named after the eponymous Norwegian explorer, who was a pioneer of oceanography in addition to an awesome list of other achievements. And he's not the only famous name to try measuring temperature at depth: one of the first known efforts was by Benjamin Franklin.