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.
In our use of digital and analogue filing tools, we classify information through folders. An article about railway construction gets filed under ‘infrastructure’ or ‘transport’. In Evernote we tag it with ‘rail’ or ‘construction’. This is thinking like a librarian and not like a writer. We are classifying the information as an input. The reason you take notes as a writer is to produce content. It makes sense, then, to take notes in line with this goal.
Traditional filing like this tends to fail when you attempt to write your content. You are stuck trying to figure out which categories will be relevant for your proposal, paper or blog post. Interesting writing often comes from connecting separate fields through a common idea. By revealing the common denominator. By unifying two seemingly-contradictory ideas. How can you possibly achieve this if you’re looking in the same category for your information? The categories simply do not fulfil the function required by the writer.
The notes you take and indeed, the way you process information, should be with a specific project or idea in mind. You must classify information in terms of its outputs. When you take notes on a book, think about how this could apply to a specific idea you had or how it argues against a paper you read last week. The premise is that you should be organising by context and always trying to connect the dots between the content you're consuming.