Some measures in pt, some in cm?

p,

I don't think it's as much technical as it is traditional. Points have been around so long that I don't think there are many takers for alternate units. Points are the native measure in Pages layout. You'll notice that sometimes you can't get objects to sit exactly on cm or inch marks, because of the base resolution being tied to the point. 72 points to the inch, so your 0,5 cm would be 14.2 points.

Someone else can comment on why a 72 pt font doesn't result in characters exactly 72 points tall on the ruler. Room for descenders perhaps?

Jerry

Message was edited by: Jerrold Green1

Jerrold Green1 wrote:
I don't think it's as much technical as it is traditional. Points have been around so long that I don't think there are many takers for alternate units. Points are the native measure in Pages layout. You'll notice that sometimes you can't get objects to sit exactly on cm or inch marks, because of the base resolution being tied to the point. 72 points to the inch, so your 0,5 cm would be 14.2 points.

Someone else can comment on why a 72 pt font doesn't result in characters exactly 72 points tall on the ruler. Room for descenders perhaps?

For a start the 72 pts used by American typesetters did not equal 1 inch. One of the many annoyingly archaic and inconsistent measures that the USA stubbornly refuses to change. Even those points have not been around for all that long, printers settled on them only in the early 20th century.

As procrastinator has pointed out the measure is of the band within which the type sits not the type itself. Some fonts closely fit the point size, others seem very small, none equal the nominal size.

Europeans have used an alternative measure, the Cicero, which Apple has ignored.

As much as America has advanced civilisation and technology in certain areas, it has also held us all back. President Ford signed the bill to convert America to the metric system and nothing much has happened since, with the exception of certain forward thinking industries making the change on their own.

About the only thing Americans can quote in metrics is a "key" of cocaine.

IMHO we should ditch all the inconsistent measures and just use millimetres (to 1 decimal place for type). Then working out sizes and their fit will become a breeze. As it is there is creeping inaccuracy as one measure is converted to another.

Peter

PeterBreis0807 wrote:
For a start the 72 pts used by American typesetters did not equal 1 inch. One of the many annoyingly archaic and inconsistent measures that the USA stubbornly refuses to change. Even those points have not been around for all that long, printers settled on them only in the early 20th century.

Peter,

Are you going to tell us what American typesetters call a point or are you going to leave it to our imagination?

I admit to putting, at times, too much faith in Wikipedia, but in their discussion of Points we can find:

+"Like the French Didot point, the traditional American printer’s point was replaced in the 1980s by the current computer-based DTP point system.+

+The desktop publishing point (DTP point) is defined as 1/72 of the Anglo-Saxon compromise inch of 1959 (25.4 mm), it is approximately 0.0139 inch or 352.8 µm. Twelve points make up a pica, and six picas make an inch."+

Jerry

To go back to source 🙂 :

From Wikipedia
*Traditional American point system*
By the (Kasson) Metric Act of 1866 (Public Law 39-183), the US (survey) foot is 1200⁄3937 m. This is 0.0002% more than 304.8 mm, which is the length of the Anglo-Saxon compromise foot of 1959, used below. A typographic foot contains 72 picas or 864 points.
Nelson C. Hawks, in 1879, used a printer’s foot of an Anglo-Saxon foot decreased by 0.375%. Therefore, the traditional ratio 7200⁄7227 (which reduces to 800⁄803) places Hawks’ point at 0.013 837 inch, or about 351.46 µm.
A second definition was proposed whereby there were exactly 996 printer’s points (= 83 picas) in 350 mm, which made the printer’s point about 0.013 848 867 inch ≈ 351.405 622 µm.
Finally, Lawrence Johnson stated in a third definition of printer’s foot that it should be 249⁄250 (99.6%) English foot. This means that the Johnson’s typographical point was 0.01383 inch, and was then converted by the 1959 value to 351.36 µm.
In 1886, the Fifteenth Meeting of the Type Founders Association of the United States approved the so-called Johnson pica be adopted as the official standard. *This makes the traditional American printer’s foot measure 11.952 inches* (303.6 mm), or 303.5808 mm exactly, *giving a point size of approximately 1⁄72.27 of an inch,* or 351.5 µm.
This is the size of the point in the TeX computer typesetting system by Donald Knuth, which predates PostScript slightly. Thus the latter unit is commonly called the TeX point.
Like the French Didot point, the traditional American printer’s point was replaced in the 1980s by the current computer-based DTP point system.

The printers had agreed to the standard earlier than I remembered, but it did take till after the turn of the century before this became the norm. There was a lot of legacy type such as woodblock and individual cast letters which would not have changed.

The invention of the Linotype hot metal system was about concurrent with the 1886 decision and may have forced it, as it required greater alignment in the forms. That I can't verify as it precedes even me, although I can remember the smell and sound of the Linotype when it was demonstrated to me in the back of an old local printers shop.

Peter