Mishneh Torah (Rambam) משנה תורה

A Torah scroll should not be written in a way which causes its length to exceed its circumference, or its circumference to exceed its length. What is the appropriate length? When the scroll is written on g'vil, six handbreadths - i.e., 24 thumbbreadths. When the scroll is written on k'laf, it may be more or less, provided that the length is equal to the circumference. If one wrote a scroll on g'vil less than six handbreadths long and concentrated one's writing, or [wrote a scroll] more than six handbreadths long and spread out one's writing, if the length is equal to the circumference, it has been written in the proper manner.

The following margins should be left [on each column]: Below the column: four thumbbreadths; above the column: three thumbbreadths; and between each column: two thumbbreadths. [To allow for these margins,] one should leave an additional thumbbreadth at the beginning and the end of each portion of parchment and room to sew the parchments together. Thus, when one sews all the portions of parchment together, there will be two thumbbreadths between each column throughout the entire scroll. One should also leave an extra portion of parchment at the beginning and the end of the scroll, to wind around its staves. All these measures are part of [performing] the mitzvah [in the optimum manner]. If one decreased or increased any of them, [the scroll] is not disqualified.

How should a person structure the scroll [he is writing] so that its length will be equal to its circumference? He should begin by making equal portions of parchment, each having a standard width of six handbreadths. Afterwards, he should wind the parchments, each in the same manner, making one tight coil. He should continue adding to the coil, winding the parchments tightly until the circumference of the coil is six handbreadths, the width of the parchment. He should measure with a red cord that [is long enough] to surround the entire coil.

Afterwards, one should make a measuring rod, forty or fifty thumbbreadths long. Each thumbbreadth on the rod should be divided into halves, thirds, and quarters, so that it will be possible to have exact measurements, including even half and quarter thumbbreadths. One should measure each piece of parchment with this rod to determine its length in thumbbreadths. In this manner, one can calculate the length in thumbbreadths of the entire coil.

Afterwards, one should take two or three other parchments [as an experiment] to check the size of one's writing. One should write a [sample] column. It is obvious that the length of the column [used for the writing] will be seventeen thumbbreadths, since three thumbbreadths are left for a margin above the column and four thumbbreadths are left for a margin below. The width of the column, however, varies according to the thickness of one's writing. Similarly, the number of lines within each column varies according to the writing. The space of a line should be left between each two lines.

After one writes the experimental column as one desires, one should measure the column with the rod. Then one should add the two thumbbreadths to be left between columns and calculate the number of columns one will have in the entire coil [should one continue] using the same [size] writing. Once one knows the number of columns [for which there is space in the coil], one should calculate according to the scroll from which one is writing whether the entire Torah will be able to be contained in the number of columns there are in the coil based on this [size] writing. If the entire Torah can be contained within this number of columns, [the scroll] will be [written in the] desired [fashion]. If, according to one's calculations, there are more columns than necessary to contain the Torah, one should write with a broader script, so that fewer columns will be included. One should write another [experimental] column [and recalculate until the calculations are resolved]. If, according to one's calculations, there are fewer columns than necessary to contain the Torah, one should write with a thinner script, so that more columns will be included. One should write another [experimental] column and recalculate until the calculations are resolved.

After one knows the width of the column and the measure of one's writing, one takes the coil [of parchment] and divides each parchment into columns according to the [size of the] column with which one experimented and made the [above] calculation, ruling each column. When more than three or four fingerbreadths remain after the final column [which fits onto] the portion of parchment, one should leave only a thumbbreadth and the space necessary to sew it and cut off the rest. One need not worry that, ultimately, additional parchments will have to be added to the coil to compensate for the portions which were cut off. This is not a factor of circumstance, because the writing will cause [the size of the scroll] to be extended [only] according to the number of columns [originally calculated].

Similarly, if one desires to make the width of the scroll more than six [thumbbreadths] or less than six [thumbbreadths], one should follow similar calculations. Thus, the length of the scroll will be equal to the circumference, neither less nor more, provided one does not err in his calculations.

The thumbbreadth mentioned in all these calculations - and in all other Torah measurements - refers to the width of a normal person's thumb. We have calculated this measure precisely and found it to be equal to the width of seven average barley-corns when placed next to each other in a cramped manner. This is equivalent to the length of two barley-corns amply spaced apart. Whenever the term "handbreadth" is mentioned, it refers to four of these thumbbreadths. Whenever the term cubit is mentioned, it refers to six handbreadths.

In the Torah scroll which I wrote, the width of each column was four thumbbreadths [with the exception of the] columns on which the Song of the Red Sea and the song Ha'azinu were written; they were six thumbbreadths wide. There were 51 lines in each column and 226 columns in the entire scroll. [In its entirety,] the scroll was approximately 1366 thumbbreadths long.

The six thumbbreadths beyond the number that one would arrive at by calculation were used for the margin of the scroll left at the beginning and the end. I wrote the scroll from parchment made from ram skin. Should one desire to write a scroll using these measurements or deviating from them only slightly - i.e., adding or subtracting two or three columns, there is no necessity to trouble oneself with calculations; without any difficulty one will have a scroll whose length is equal to its circumference.

One should not write fewer than three columns on a piece of parchment, nor [should one write] more than eight columns. If one has a piece of parchment large enough to contain nine columns, one should divide it in two, one portion containing five columns, and one portion four columns. When does the above apply? At the beginning of the scroll or in the middle. At the end of the scroll, however, even if there is one verse in one column, that column may be written on a separate piece of parchment and sewn together with the other parchments.

When one sews the parchments together, one should use only sinews from a kosher species of animal or beast. [Sinews taken from] animals which died without being ritually slaughtered or which were killed by wild beasts [are, nevertheless, acceptable]. This is a halachah transmitted to Moses on Mount Sinai. Therefore, if one did not sew them with sinews, or used sinews from a non-kosher animal, the scroll is unacceptable until one removes the threads and sews them again.

When sewing all the pieces of parchment together, one should not sew the entire length of the parchment. Rather, one should leave a certain portion unsewn on both the top and bottom of the parchment, so that the parchment will not tear in the middle when the Torah is rolled. Two staves of wood should be made for a [Torah scroll], one at the beginning and one at the end. One should sew the parchment left over at the beginning and the end [of the scrolls] to these staves with sinews, so that it can be rolled around [these staves]. Space should be left between the staves and the columns of writing.

When a tear in a Torah scroll is contained within two lines, [it is sufficient to] sew [the tear]. If it [extends to] three [or more], [it] should not be sewn. When does the above apply? With regard to an old Torah scroll which one cannot recognize as having been processed with gallnut juice. If, however, one can recognize that the parchment was processed with gallnut juice, one may sew it, even if the tear extends to three [lines]. Similarly, [if there is a tear] between columns or between words, one may sew it. All these tears may be sewn only with the sinews which are used to sew the parchments together. When sewing, one must be careful that a single letter is not omitted or has its form distorted.