Sieve

William Gouge once wrote about verse 13 of Psalm 106: As it is with a sieve or boulter, the good corn and fine flour goes through, but the light chaff and coarse bran remains behind; or as a strainer, that the sweet liquor is strained out, but the dregs are left behind: or as a grate, that lets the pure water run away, but if there be any straws, sticks, mud, or filth, that it holds. Thus it is with most men's memories; by nature they are but, as it were, pertusa dolia, mere river tubs, especially in good things very treacherous, so that the vain conceits of men are apt to be held in, when divine instructions and gracious promises run through; trifles and toys, and worldly things, they are apt to remember, tenacious enough; but for spiritual things they leak out; like Israel, they soon forget them. 

Apart from the Latin phrase, pertusa dolia, which Gouge translates as 'mere river tubs', what other word is unusual in this extract?  It's the word, 'boulter' which I can't say I've ever come across before. Plainly it's a word meaning some form of sieve, and the phrase, boulter-cloth, appears in a some places in an old recipe book, The Closet of Sir Kenelm Digby Knight Opened.  It seems to mean a cloth that you squeeze juices through, as we strain blackcurrant juice through a muslin cloth, sometimes. 

While I might not have met with a 'boulter' before (at least not by that name) I thought I knew what a sieve was.  But when I went to check out one site I discovered that there are sieves used for scientific work that are nothing like the affordable sieves I use at home with cooking or baking.  These ones are expensive models that use metal mesh on several different levels (like a kind of tower) through which various materials are gradually sifted.  They're often called 'test sieve shakers' because they're shaken electrically (presumably at high speeds) and do the work in a short time that would take a scientist days.  As you can see from the picture, they're rather more intricate than the average household model...