Not all the towers along a transmission line are identical. Look closely at a tower where the line makes a sharp turn and you will likely find it is wider and beefier than other towers along the route. The added strength and weight are needed to resist the unbalanced pull of the conductors, which might overturn an ordinary tower. These special towers are called deviation or angle towers.
The transmission-line tower everybody knows is an Erector Set latticework of steel girders and diagonal braces. The techniques for designing and building these towers are the same ones used in constructing steel bridge trusses or crane booms. The individual pieces can be made cheaply from rolled steel and then bolted together on the site. This last point is more important than it might seem: transporting a fully assembled tower 100 feet tall is an awkward and expensive business.
I worked for several years as a leader of birding tours, and I have met a few sad individuals who were so focused on adding to their life lists that they would refuse to look at a bird species that they had seen before, no matter how spectacular the view or how fascinating its behavior of the moment might be. “I don’t need that bird” was their standard reply.
For a person just getting started in some area of natural history, and unabashed focus on list-chasing is a good thing, at least for a while. The trick is knowing when to stop.
Keith Brown described how he got the idea “that the maximization of daily species lists of butterflies, a seemingly unscientific goal (though much employed in a sister area, ornithology), could give a large scientific fallout."
For example, he described how six weeks’ effort in the Brazilian central plateau had turned up twenty-five species previously unknown for the area—but then he had adopted the “maximization” method, and in another six weeks, he had found nearly three hundred more species.