[JT118]

Thinking; driving into work this morning, that it is likely this gauge was calibrated to imperial units. It seems unlikely to me that anyone who put it together from a box of bits would bother to put seals on etc.

It seems to me to be more likely that the gauge had the makers plate removed when a changeover from imperial to metric occurred in some institution so that it wasn’t used and put into a store for the next 35 years.

A suggestion, before you break the seals; put 0.254 into the TX config file and then do a few runs of 314 and 628ml.

In theory if it has been calibrated to imperial units then each tip will be 5.08ml and represent 0.254mm of rain.

Therefore it should take 40 tips (39.878 actually ) to register 10 mm rain using 314ml of water.

If after a few runs of 314ml and 628ml you don’t get the required result with the tolerances specified ie: 3 to 4% then go ahead and break the seals and get the gauge back to metric.

One last thing, if you do break the seals, try to reseal once you have adjusted, the seal acts as both a thread locker as well as a visual aid to check if the instrument has been tampered with.