Measurements relating to a sefer Torah – columns & lines
1. One does not make a sefer Torah’s height greater than its diameter, nor its diameter greater than its height. That is, one should plan for a string encircling all the sheets of the sefer (when sewn and rolled) to be just the same length as the height. This is because of “Zeh eli ve-anvehu” – if it is overly high or overly fat it won’t look very nice. How high should it be? On gevil, six tefaḥim, like the stone tablets were (Mordekhai). This is twenty-four etzbaot (the width of the average thumb, or seven average barley grains placed snugly one next to the other, or two placed end-to-end (Rambam)). On klaf, a bit more or a bit less provided its height is the same as its diameter. Also, if one made a bit less than six tefaḥim on gevil and wrote smaller, or a bit more than six tefaḥim and wrote larger, this is perfectly fine. Some say that the roller in the middle of the sefer is counted as part of the diameter (Tosafot, Ro”sh) but it must be of average size (Shita Mekubetzet), and some say that it is not (Rambam), which appears to be correct.
2. The length of each line (except for the columns containing the Songs) is thirty letters, or enough to write “lemishpaḥoteihem” three times. We don’t make it less than this lest the column resemble a missive, and we don’t make it more than this because then one’s eyes become distracted by the length of the line and it is more likely that he will make a mistake at the beginning of the line [ie the reader will lose his place]. This applies specifically to narrow writing; with chunky writing one does whatever will look good, and he won’t get confused because the writing is large (R”T and Rabeinu Ḥananel), and this is the custom.
3. It is the custom to have no fewer than 48 lines, representing the journeys of Israel, and some say no fewer than 42, because of what God did in the Sinai wilderness at Kadesh. Also, we don’t have more than 60 lines, representing the 60 myriads of Israel who received the Torah. This is because the beginnings of sanctity start at 48 or 42 (the wanderings in the wilderness) and continue to 60 (the giving of the Torah). If one makes it different it isn’t invalid. It is the custom to rule an additional line at the bottom, which is not written on at all, and this too is not critical to its validity.
4. One sheet should have no fewer than three and no more than eight columns. If one happened to have a sheet with nine columns, he shouldn’t cut it into a sheet of six and a sheet of three, but should make a sheet of four and a sheet of five, because that looks nicer (Tur). This applies to all the sheets in the sefer except the last one; at the end of the sefer, even if there is only one verse, one writes it in a single column and sews this to the other sheets. The last verse does not have as many words as there are lines on the sheet, so he should stretch the letters of one word vertically over four or five lines, so as to finish at the end of the column. If there are several verses he should write one word per line on as many lines as necessary. All this applies only as an absolute last resort.
5. The Torah must come to its conclusion in the middle of the line, at the bottom of the column, so everyone knows that this is the end of the Torah, which they would not do if it went to the end of the line. If it did go to the end of the line, some say that the sefer is invalid (Be-er Sheva), and some say it is valid (Panim Me-orot), which appears to be correct.