This week, the Collected Wisdom gang is heading out to the Prairies looking for work as lumberjacks. We’re bound to make a fortune!
Why do so few trees grow on the Prairies? Joanne Helmer of Yellow Grass, Sask., wants to know.
It’s because, while the prairie climate is temperate enough for trees, there just isn’t enough rainfall, writes D. Scott Munro, a retired professor of geography at the University of Toronto at Mississauga.
Trees do best in the temperate climates of southern Canada and the mid-to-northern United States, he says, wherever more than 500 millimetres of precipitation falls each year. This tends to be the least amount needed to satisfy their annual water requirements. “Less than this amount falls across the Canadian Prairies and the Great Plains of the United States,” he writes, “where naturally occurring grasses, which require less water than trees, covered the land until they were replaced by agricultural development.”
To the extent that naturally occurring trees exist in the Prairies, they tend to be found in river valleys, such as those of the Assiniboine, Qu’Appelle and South Saskatchewan systems, “where streams supply what the sky cannot,” he says.
Why, in this wireless age, do all the Major League Baseball dugouts have phones wired into the bullpens? asks Jack Herrington of Peterborough, Ont.
Richard McDonell of Red Deer, Alta., pitches this idea as a possible explanation. “I was making a local call recently on my one-or-two-year-old wireless phone, which had just come off the battery charger, when for no clear reason, it went dead,” he writes. “Its predecessor had lasted perhaps three years.”
He says the phones you see in baseball parks were probably installed when the stadiums were built, and “as they have continued to function as needed, year after year, there has been no reason to replace them with high-tech units that have an expected lifespan similar to that of a pitcher with a sore shoulder.”
Last week, we told you how to find out how much propane there is in a barbecue tank. The propane in the tank is colder than the surrounding air, we said, so pour hot water down one side of the tank. The metal will feel warm where there is air in the tank and cold where the propane level starts.
Well, while the water trick works, the underlying explanation was – how can we put this best? – wrong.
First, the contents of the barbecue tank are liquid propane and propane vapour, not propane and air. Also, writes David Graham of Montreal, the propane can’t be colder than the surrounding air (for long, anyway) without violating the laws of physics. And, heaven knows, we wouldn’t want to do that.
The full portion of the tank feels colder because the propane conducts heat much better than the vapour does. “This ‘sucks’ heat out of your finger if you touch the tank at a level where there is propane.”
Why does natural gas – in my stove, for example – burn with a blue flame, whereas most other flames are yellow or red? asks Ross Smith of Courtenay, B.C.
Peter B. Scully of Toronto writes: “How did navy guns compensate for the bucking and rolling of the ship as they attempted to hit enemy targets prior to radar and automatic gyroscopic compensation?”
Can zebras be trained like horses? asks Jackie Phillips of Toronto.