Just returned from a week in Belize, which is a tiny country with only 240,000 citizens. It is interesting that although the country is officially metric, most measurements (at least in the tourist areas) are in ifp. This is undoubtedly true due to the earlier British status of the country and the present influence of American tourist trade, which is the country's largest source of revenue. I noted that the water meters are in gallons, temperatures are given in deg. F, depths for scuba diving are in feet, and even the baggage scales at American Airlines at the airport were in pounds (although the ones at the international airport terminal in Dallas were in kg). People referred to distances in miles. It is interesting that for scuba, divers must know that pressure increases one atmosphere every 33 feet (as taught in the US), which is, of course, 10 m. The usual safe diving limit is around 100 feet, which is rounded off to around 30 m. Not being a physicist, I wonder what relation there is between air/water pressure doubling at exactly 10 m depth, and adding another atmosphere at 20 m. Anyone know? Why 10 m and not 9 or 11? The new scuba documents published by PADI and DAN (two scuba organizations in the US) now give dual measurements (xx feet/ yy m). It is critical that divers know their depth at all times, and for this one refers to his or her depth gage, which is attached to the regulator. All the ones I have ever seen are in feet only, although I imagine that European divers use ones in meters. I did hear two Norwegians once discuss their diving in meters. HARRY WYETH
