Cambridge Underground 1985 pp 24-28

Notes on Survey Draftmanship

by Philip Sargent

There are 4 golden rules:

Preferably use stencils to the International Standards Organisation typeface (ISO 3098/1, the same as DIN 6776), either 'upright' or 'oblique'. If using dry-transfer lettering, use LETRASET and not one of the cheap imitations, some of which have skewed letters and no alignment marks. With letraset use 'Univers#67' or 'Univers#55' typeface.

Founts: Whys and Wherefores

There are hundreds of different character founts (typefaces) available in letraset and we have generally used 'Univers#67' on the cover of Cambridge Underground. The surveys drawn by Julian of water tracing and diving in Yorkshire and Greece also used this. For fine work it is a bit heavy as the letters have a line-width to character-height ratio of about 5, so while it is excellent for titles, the somewhat thinner Univers#55 is better for labelling pitch heights, climbs and names of chambers. In the interest of clarity we should perhaps change to Univers#55 for everything, once our current letraset stocks are used up.

As far as stencils go, there are 3 commonly available standards: ISO, DIN#17/1, and DIN#1451. If you have an old stencil it is probably DIN#1451 which has a line to height ratio of 7, the other two have a ratio of 10, which is much better for small script. DIN#17/1 looks very similar to DIN#1451 with the sole exception that the lines are thinner, whereas the ISO set is quite different. ISO letters have been designed specifically for ease of use with stencils and for lack of ambiguity, they have lines meeting nearly at right-angles in order to prevent ink pooling in the vertices, and '3' and '8' are distinctively different, as are 'zero' and '0'. The two thinner stencil types can use the same set of pens, but DIN#1451 uses a different set of nib sizes, and you cannot use a pen from one sort in a stencil from the other without producing an untidy mess (see first golden rule).

Size of Original

The normal situation when drawing up a survey is to draw it large for reduction to A4 in Cambridge Underground, and possibly to A5 in Caves and Caving. I suggest that unless you have very good reason, the original artwork should NOT be bigger than A3, and for most surveys there is absolutely no reason why it should not be drawn the same size as for final reproduction. Although the reduction makes a few tippex marks marginally less noticeable, the degradation in quality caused by the extra copying step removes this advantage; much more important is the strong probability that the lettering becomes less readable either because a fount with too low a height:line-width ratio was used, or because the labelling was done too small or too close to the cave drawing. (Tippex is a pain, much better is to scrape away the ink from the top surface of the tracing paper). All the problems of imagining what it would look like after reduction disappear if you make it 1:1 to start off with. In all that follows, however, I will assume that you are drawing at A4 or A3 for reduction by at most a factor of two (A3 to A5 is a factor of two, A4 is related to either by a factor of root-two).

Pens and Linewidths

It will be assumed here that the ISO lettering style is used (which is the future world standard anyway), so pen widths will be given from among the ISO standard range: 0.13, 0.18, 0.25, 0.35, 0.5, 0.7, 1.0, 1.4, and 2.0mm diameter nib. These nib sizes are related to each other by, very nearly, a factor of root-two. This is so that even after a reduction or enlargement from, say, A3 to A4, it is possible to make additions or corrections with a correctly-sized pen. (Many copiers, especially the Minolta type, can xerox onto tracing paper, and the copied ink can be scraped off for corrections very easily).

Generally use 0.35 or 0.5mm pens for the smallest lettering (which corresponds to characters 3.5 or 5mm high of course). Use the same 0.35 or 0.5mm pens for the passage sides, and a smaller diameter, 0.35 or 0.25, for the features such as rocks, stal, mud, streamway etc. Use either the same size as that, or a smaller pen (0.25 or 0.18mm) for shading sumps, pools and ducks, and for drawing the line of the rigging on elevations (see the survey of 1623/144 in Cambridge Underground 84 for a very good example of this). Mark permanent survey stations, which should always exist at the entrance and, if it is a deep cave with possible extensions, also far down towards the bottom, as small triangles using the smallest pen you have used so far. These stations should, for unambiguity, be artificial. There are usually plenty of bolts, so use one of them. In the big chamber at the junction of the Inlet Pitches, Pete's Purgatory; the Futility Series and the Purgatory Bypass in 115-41, there is a permanent station which is a single bolt-hole (no bolt) in a prominent rock. If it becomes a popular tourist trip (!), this could perhaps be filled with mud for aesthetic reasons.

The name of the cave should be in the largest type, using a 0.7mm pen. The area in which it is found should be written smaller (0.5mm) and then the altitude of the entrance, the surveyed depth, CUCC and date, BCRA grade and the names of the surveyers in 0.35mm. If drawing for 1:1 reproduction, these can be scaled down one size.

Don't use rotring pens of the "micronorm", "varient", or "varioscript" types because they are an older design and dry up after a few weeks disuse. The "2000#isograph" series, however, need cleaning far less often, this is apart from being useful because they are ISO sizes. When cleaning drawing pens, soak in warm water with washing-up liquid in it, dismantle after soaking and wash in the same water. Adding alcohol doesn't help, and acetone dissolves the working parts.

Survey Layout

Try to draw both plan and elevation on a single sheet and in correspondence up the length or across the width of the paper, ie. if it is an elevation on the eastwest section, with west running across the paper to the right, then draw the plan beneath it, also with west running to the right. This makes it much easier to get an idea of the overall passage shape because it is then simple to look at a feature on both sections in quick succession. On elevations always say whether it is a projected or an extended elevation, and if projected, say which compass bearing it is projected onto.

Draw a length scale in alternate shaded bar form, with 5 or 10 subdivisions, and put a depth-below-entrance scale on one side of the elevation. If the cave is in an area where more caves can reasonably be expected to be discovered, then also put an altitude scale above sea level on the other side of the elevation. In such a case it might be worthwhile drawing the system at a scale which is the same as that used for other caves in the area, rather than one which would be ideally suited to showing off the features of that particular cave. This is less important now that there are variable-magnification Minolta copiers available in Cambridge, so scale ajustment for area maps can be done in a single step with magnifications anywhere between 0.640 and 1.420, accurate to about a tenth of a percent.

If you don't wish to put your name on the survey in big letters, you should at least put your initials and date at the bottom somewhere, in case of queries later, perhaps years later. If a computing package has been used for the centre line then give its name and version number, e.g. 'centre line drawn by SU#5.13c at Cambridge'. The SU package which Andy Waddington wrote is available on two mainframes but with different plotting packages, and is also running on his Acorn BBC-B.

If the survey is a very large one, intended for poster-size reproduction, then make sure that the smallest lettering will not be less than 2.5mm high after reproduction. You may also like to state on the survey the scale at which it was originally drawn, since it may get copied from publication to newsletter to carrier pigeon letter, and the eventual recipient could be extremely interested in knowing if a larger (and clearer) version of the survey exists. It is much neater if the whole thing is put in a box: use the 0.35 or 0.25mm pen for this.

More on Typefaces

Using different typefaces on the same survey is sometimes unavoidable, for reasons of availability, expense or speed. If you have to, at least keep the sizes of the two typefaces quite different. Thus Univers#67 heading at 9.5mm is fine, but then don't use both 6.5mm Univers#67 and 5mm ISO stencil. The only exception to this rule is when you use the oblique version of the same typeface. Univers#56 is the oblique version of Univers#55, and the ISO stencils (but not the others) also come in oblique versions.

The size of stencil lettering is stated in mm as the height of the capital letters, but the sizes of character founts in printing and on letraset are given in 'points', where 48pt is 13mm, 36pt is 9.5mm, 18pt is 5mm, and 14pt is 3mm (see below). Founts are available in letraset in dozens of different sizes, and sometimes in white as well as black. The availability of the size you want of the fount you want depends on the size of your local drawing shop. Even Heffers doesn't keep the entire range at its King Street shop.


Much of the above may seem irrelevant to those who have been drawing surveys for years and have found a style that they are happy with, not to mention already having a complete set of expensive stencils.

The recommendation of drawing at 1:1 times the final scale may come as a surprise to some, but you don't need an incredibly steady hand to do quite detailed work if you have a fine pen and use good quality paper. It saves a lot of time in the long run, when the problems of converting artwork into the finished product are taken into account.

Footnote: [ Strictly speaking, there are 72 points to one inch, but the point size of a font is not the actual height of any letter, but of the 'scaffold' on which the letters are constructed. This means that two different fonts of the same font size may well have different sized letters. The figures Phil quotes above for the sizes of a 48pt font, etc. are correct for the particular fonts he recommends - don't be confused into believing that a 36pt font will always have ½" high letters ! Webeditor, 1998 ]

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