OF GAGING AND TABLING

COMMON BREWERS' UTENSILS.

WHEN an Officer of Excise visits a Brewhouse for the purpose of gaging and fixing the utensils, the most regular method of proceeding is, to begin at the upper part of the house with the Coppers, and finish below with the Backs and Squares.

For this reason we shall begin with a COPPER.

PROBLEM I.

To Gage and Inch a Copper.

Most of the Coppers used by common brewers have the bottom in the form of a spherical segment, sometimes of greater, and sometimes of less altitude; the

convex part generally projecting upwards into the Copper, when it has the name of a Rising Crown; but at other times the convexity projecting downwards (and of course leaving a concave space within,) when it is termed a Falling Crown.

Coppers with flat bottoms are very seldom made; and of large Coppers, those with rising crowns are more frequently met with than any others. We shall, therefore, treat first of a Copper with a rising crown.

CASE I.

Of a Copper with a Rising Crown.

METHOD OF GAGING.

Lay a straight pole or rod diametrically across the mouth of the Copper, or, where that cannot conveniently be done, extend a small cord like a diameter across the mouth, causing it to be held tight in that situation. Then along this cord or rod move a line, furnished with a plummet, till the lead hangs directly over the centre of the crown, and with a dimensioncane take the perpendicular distance between the centre of the crown and the cord at the level of the mouth; this distance will be the depth of the Copper in the middle. Again, slide the plumb-line along the rod or cord above, till the plummet hangs freely over the lowest part of the bottom of the Copper, just at the beginning of the convexity of the crown, where the crown rises from the sides. And with a rule, or

dimension-cane, take the length of this perpendicular also; then without shifting the line, measure the distance it has been moved from the middle of the cord or rod, since the first perpendicular was taken. Twice this distance will be the diameter of the base of the spherical segment forming the crown, and the difference of the two perpendiculars will evidently be the altitude of the segment, or rise of the crown.

The next step is to take two cross diameters of the Copper within, at the level of the highest part of the crown, first striking a mark at that level all round the Copper with a pair of compasses. Those cross diameters being added together, and the sum divided by 2, will quote the mean diameter of the Copper, at the level of the top of the crown. This mean diameter multiplied by the decimal 707 (see page 135,) will give the side of the inscribed square for the circle described round the Copper at the level of the crownhead. Having, therefore, either by the pen or Sliding Rule, found the side of this square, extend a slidingcane or a tape to the exact length, and mark the Copper with chalk at the four angles of the square, precisely level with the top of the crown; that is, on the circle described with the compasses.

If the Copper be large, a lighted candle is now to be set on the centre of the crown, and the Copper darkened from without. Then a plumb-line is to be held between the candle and each of the four marks at the angles of the square, so that the shadow of the line may be chalked down the sides of the Copper all the

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way from the level of the mouth, to the circle described with the compasses.

In these chalk-lines will be the extremities of the cross diameters, which are to be taken at stated altitudes above the centre of the crown, or, more properly, at stated depths below the level of the mouth.

To determine the place of these diameters, lay off ten-inch distances along one of the chalked lines, beginning at the level of the crown head, if the altitude consist of integral inches, (but if not, beginning at such distance above the crown, as shall leave the altitude the greatest whole number in inches,) and with these ten-inch distances proceed up to the mouth. Then half way between each of those distances will be the place of the cross diameters. Wherefore make a mark at the half of each distance, transferring the several altitudes of the last marks to the other three lines, and at these middle distances take cross diameters, considering the half of each pair as the mean diameter of the Copper at that depth. These mean diameters are to be transferred into the Dimension Book, and severally placed opposite the depths at which they were taken.

Although we have here recommended the distances to be taken from the bottom upwards, we would be understood, that in reality, the divisions begin at the mouth but since we leave all odd tenths at the bottom, and are not confined to any particular number of inches in either the first or last division, this method of beginning below is not attended with any inconveni

ence. We shall, however, for the sake of variety, and, perhaps, as the best practical mode for a Copper, begin, in all our examples except the first, at the level of the mouth.

It may here be observed, that when we begin at the bottom, and the ten-inch distances laid off, end not at the mouth, but within a few inches of the mouth, it is customary, but not on that account necessary, to consider the upper half of the last ten inches, and the portion of the Copper above it, as one division, making a mark at the half of its altitude; and in this case we carry the other marks severally to all the tens below, instead of making new marks at the middle of each ten: we may now take the mean of the cross diameters at the top of the crown, as the diameter of the lowermost division including the crown, provided we calculate, by the pen, the quantity of liquor required to cover the crown: but if we ascertain this quantity by measure, then the last pair of cross diameters is not taken close to the crown, but about two inches and a half above it, that is, at the middle of the lowermost division of the Copper, whatever it may be, excluding the crown. This division evidently can never be less than five inches, nor so much as six inches.

In all cases of gaging Coppers, odd tenths, on the depth, as we have already stated, are to be left at the bottom, as they would otherwise occasion much trouble in the calculation.

Having ascertained the several cross diameters, and found the arithmetical mean between each pair, we