Chap. 6.]

Modern, Siphons,

523

246 and 247 are copies. Both are designed to show the application ofthese instruments for transferring large quantities of water over risinggrounds, as mentioned by Heron . No. 246 is formed entirely of woodenplanks strongly nailed together. The upper ends of the two trunks orpipes are United to a square and close box, by means of which they werecharged through the opemng on the top. The lower orifices were tem-porarily closed by plugs, figured below with short ropes attached. Whenthe whole was filled, the hole at the top was closed by driving in the Stop-per, figured near it, and then the two plugs below were withdrawn bymeans of the ropes.

There is little doubt that large siphons made of planks and jointed orlined with pitch would work well, even if they were not perfectly tight,provided the orifice of the discharging leg was considerably lower thanthe surface of the water in which the short leg was placed.

Heron directed large siphons to be filled through a funnel at the top,and the orifices closed below, as represented in Nos. 246 and 247.

No. 247 was of metal, but charged like the last by means of a woodenbox ; the opening to admit the water and its Stopper being clearly repre-sented. There appears no device for closing the lower ends of thissiphon; and as they enter the water perpendicularly, the plugs and ropesused in No. 246 would hardly apply. Probably the short leg was closedby a valve opening upwards at the bottom of the box, on which accountthe latter was made conical to afford room for it to play. This valvewould be sufficient for the purpose of charging the siphon, provided theupper part of the box was higher than any other part of the Instrument.We therefore suppose that the disproportionate size of the box and itsbeing figured below the bend are errors of the artist.

Of modern improrements, the addition of sucking tubes by which smallsiphons are now commonly charged was the first. It is uncertain whenor by whom they were introduced. They do not appear to have beenmuch used, if at all, before the early part of the last Century ; for all thesiphons described in old treatises on chemistry, distilling, &c. invariablyconsist of single tubes, which were either charged by immersing them, orby drawing out the air from the orifice of the discharging leg by themouth. It may contribute to some future history of the siphon to preservea few of these.

Nos. 348. 249.

The first two are from the English translation of one of Conrad Gesner ’sworks, Lond. 1599. (See page 381 of this volume.) Speaking of draw-ing off water from the head of a still, the author observes, “ You may putcertaine draymg pipes into the cover such as you see here livelie portray-ed.” Copies of the same are inserted in several other old works. In“ Maison Rustique,” Paris, 1574, folio 217, they are to be seen, and theinstruments are said to have been made of tin platep (tuya.ux de fer blanc.)

a This beautifnl mannfacture (tin plate) which contributes so largely to the furnishingof our kitchens, &c. is supposed to be of aneient date. The Germans were the firstmakers of it in modern times.