The felts which convey the paper are omitted so as to get a clearer view of the molds.] HARPER MACHINE.--There is a type of Fourdrinier called the Harper which differs from it in that it is turned end for end. A long felt carries the paper from the couch rolls back over the Fourdrinier part, delivering it to the first press. This is considered advantageous in making very light papers which otherwise are with difficulty led from the couch to the press rolls and are apt to break down in the passage. YANKEE MACHINE.--There is even one type of machine known as the “Yankee” which has but one drier of very large diameter. This is used in making machine-glazed wrapping papers, which are very smooth on the side of the sheet which comes in contact with the drier and rough on the other side. The “wet” end of this machine is a Fourdrinier type. The arrangement and number of smoothing and calender rolls is also dependent on the class of paper to be made. Most writing-paper machines have no calenders at all as the surface is obtained on special machinery such as platers and sheet calenders after the paper comes from the drying loft. One can easily appreciate that, while the general principles of all paper-making are identical, there is a call for a wide variety of arrangements, such as those cited, to meet the varying requirements of different classes of paper. SURFACE SIZING.--Surface sizing, or animal sizing, necessitates a vat with squeeze rolls. The paper is first run over enough driers to dry it; then introduced into the vat of hot size. On the cheaper grades the size is dried on the machine by a special skeleton drying apparatus, but the better grades are cut off and piled up by the “lay-boy” at the end of the machine, then transferred to drying lofts and hung up over poles to dry. Hence the term “loft-dried.” Any special finish has then to be applied sheet by sheet. FINISHING PAPER.--Finishing paper is accomplished either on the paper-machine itself, or after the paper is turned off on the machine it may be treated by special apparatus. WOVE AND LAID PAPERS.--A so-called wove paper is made with a plain dandy, covered with fine wire cloth the same texture all over. Laid paper is really a water-marked paper, in which the whole surface is marked by a specially constructed dandy which imprints a mark in imitation of the early hand molds. There are heavy lines running with the grain of the paper and lighter lines running across. ANTIQUE.--An “antique” surface is obtained by skipping the calender rolls and leaving the paper rough as it comes off the felt to the driers. A medium finish is obtained by a slight calendering, while the highest machine finish, and the so-called English finish, is obtained by a heavy calendering.