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.
Generally speaking (and ignoring questions of styling, API availability, etc.), an ideal Web annotation pattern follows these principles:
Annotations appear in close visual proximity to the primary content.
Their design neither distracts from nor hides the primary content.
The preceding principles are followed regardless of screen width.
The only pattern I’ve found that meets these criteria is FiveThirtyEight’s.
...As it turns out, FiveThirtyEight didn't invent this pattern. It likely originated in medieval illuminated manuscripts which contain “interleave notes” — comments written literally between the lines.