Here are some one liners...
Nothing Plows Like a Deere -- John Deere is a blacksmith who moves to Moline and makes history with his steel plow.
Two Horses' Backsides Produce a Standard Gage Rail -- Selecting the width between the rails means doing what the Romans do.
In Other News -- Kerosene, hypnotism and the saxophone.
Nothing Plows Like a DeereJohn Deere is a blacksmith living in Grand Detour, Illinois. A few years ago he found a broken saw blade made of Scottish steel and turned it into a self-scouring plow blade. Prairie land requires a different kind of plowshare or cutting blade. The prairie grasses form a tight-knit barrier against the wood and iron plowshares of the 1840s. The soil is sticky and farmers must stop frequently to clean the primitive wooden blades. Iron plowshares are heavy and brittle and often break. Four to six oxen are used to pull the heavy plows through the prairie soil just to break it up followed by smaller plows to do the fine work. Steel is stronger and more flexible. It can cut straight furrows without having to plow it twice and John Deere plows are small enough to be pulled by one horse. Importing steel from overseas makes the plows more expensive, so John is making use of local steel when available. (It really is available in the Midwest in the 1840s.) Sales are good but now he wants to open a factory. The town of Moline is positioned close to the larger cities for more sales opportunities and the Mississippi river will lower shipping costs. He moves his family to Moline and starts a full-blown factory operation. Nothing plows like a Deere.  
Two Horses' Backsides Produce a Standard Gage RailTrains need a standard gauge. A wider gauge means more stability but requires wider curves to safely turn and more work on the underlying base below the tracks. A narrow gauge allows for quicker turns in tight situations. That is why you see mining cars that look like toy trains at the park. Also when a train follows a curve, a corner of the train cab always swings out beyond the rail. Too tight a curve means that the corner swings out a lot. If a light pole is set too close to the tracks, it is toast. Standardization also makes expansion through acquisition easier. If I own a successful railway route and I want to expand, I can lay more track or I can buy out my competitor on that same route and use their existing track for my own trains... if they are using the same gauge. Different gauges means work converting the rails or time transferring cargo and passengers from one train to another. So what is the solution? Early trollies were pulled by horse teams, usually two horses pulling side by side. Thus the rails gauge was measured as the width across the backside of two horses which is 4 feet, 8.5 inches. This becomes the standard gauge for train tracks.  
In Other News
- The saxophone is patented in Belgium. Music has just become slow, sweet and silky. A population explosion is near at hand. All hail Adolphe Sax!