In physics, fields describe the distribution of forces in space. Their description thus requires the knowledge of magnitude and direction. Both are expressed through field contours; field forces act in the direction of the contours, and the distance between the contours indicates their magnitude. (The closer the contours are together, the larger the force.) In an electric field the direction of the field is given by the electric charge of the charged sources. If the charge is negative, the field is directed toward the charge. All electric fields begin on a positive charge and end on a negative charge. If two positive charges interact, their forces are directed against each other. This creates a repellent force as shown in the illustration. (The same occurs with two negative charges, because their respective forces also act in opposite directions.)

One of Murray’s most helpful advisers on American words was aGerman living in Boston, Carl Wilhelm Ernst. Ernst was a journalist, theeditor of the Beacon newspaper, and a former Lutheran minister who hadmoved to America when he was eighteen years old. Murray wrote to thejournalist in a panic when completing the entry for public school. ‘In workingat this, I overlooked the fact that we had nothing for the US use, and findmyself now almost stranded, and unable to complete the article.’ He wrote toErnst asking for illustrative quotations and for clarification on the Americansense of the word: ‘It is said to be synonymous with Common School. I donot know which of these is the official appellation, and which the popular, orwhether they are both so used. We should like to know this. The designationin England has a long and rather complicated history coming down from theL. publican schola, which is already used by Jerome of Quintilian.’Murray started the entry by defining the use of public school in Englandas ‘originally a grammar-school founded or endowed for the use or benefit ofthe public’ but more recently, in the nineteenth century, as ‘the old endowedgrammar-schools as have developed into large boarding-schools, drawingfrom the well-to-do classes of all parts of the country or of the empire’. Henoted that ‘the ancient endowed grammar-schools or colleges of Eton,Winchester, Westminster, Harrow, Rugby, Charterhouse, Shrewsbury’ aresometimes referred to as ‘the Seven Public Schools’. He contrasted this senseof public school with that in Scotland, the British colonies and the UnitedStates of America, as a school provided at the public expense, usually free.Above six American quotations spanning from 1644 to 1903, Murray added alengthy note, thanks to Ernst’s advice, ‘The term has been used in NewEngland and Pennsylvania from the 17th c., and has been adopted in all Statesof the American Union. An early synonym was “free school”, and a later onein some States, “common school” which is now however generally confined toa school of the lowest grade or “public elementary school”.’

This search for order pushes one to seek out under-lying patterns and trends, to find relations that may betypical and causal.

here are several ways I havefound useful to invite the sociological imagination:

And dry grass singing

They took the air and they swarmed as one

we must be able to employ persuasion, just as strict reasoning can be employed, on opposite sides of a question, not in order that we may in practice employ it in both ways (for we must not make people believe what is wrong), but in order that we may see clearly what the facts are, and that, if another man argues unfairly, we on our part may be able to confute him. No other of the arts draws opposite conclusions: dialectic and rhetoric alone do this.