Each applicant for a patent is required by law to furnish a drawing of
his invention whenever the nature of the case admits of it. The drawing
must be signed by the inventor or the name of the inventor may be signed
on the drawing by his attorney-in-fact, and in either case must be
attested by two witnesses. The drawing must show every feature of the
invention covered by the claims.
When the invention consists of an improvement on an old machine, the
drawing must exhibit, in one or more views, the invention proper,
disconnected from the old structure, and also, in another view, so much
only of the old structure as will clearly show the connection of the
invention with the old machine.
Several editions of the patent-drawings are printed, the smallest of
which is about 3 × 4³⁄₄ inches, so that the drawing must be so made that
it will stand a reduction of about one-fourth. This work is done by the
photo-lithographic process, and therefore the character of the original
drawing must be brought as nearly as possible to a uniform standard of
excellence suited to the requirements of the process.
NOTE.--These rules will be found most useful to many readers of this
work--hence their introduction at this point. Nearly 50,000 patents
are “applied for” in the United States every year.
The following rules are given by the Patent Office for guidance:
1. Drawings must be made upon pure white paper of a thickness
corresponding to three-sheet Bristol board. The surface of the paper
must be calendered and smooth. India ink alone must be used, so as to
secure perfectly black and solid lines.
2. The size of a sheet on which a drawing is made must be exactly 10 ×
15 inches. One inch from its edges a single marginal line is to be
drawn, leaving the “sight” precisely 8 × 13 inches. Within this margin
all work and signatures must be included. One of the shorter sides of
the sheet is regarded as its top, and measuring downwardly from the
marginal line, a space of not less than 1¹⁄₄ inches is to be left blank
for the heading of title, name, number and date.
3. All drawings must be made with the pen only. Every line and letter,
signature included, must be absolutely black. This direction applies to
all lines, however fine, to shading, and to lines representing cut
surfaces in sectional views. All lines must be clean, sharp, and solid,
and they must not be too fine or crowded. Surface shading, when used,
should be open. Sectional shading should be made by oblique parallel
lines about ¹⁄₂₀ of an inch apart. Solid black should not be used for
sectional or surface shading.
4. Drawing must be made of the fewest lines possible, consistent with
cleanness. The plane upon which a sectional view is taken should be
indicated by a broken or dotted line. Heavy lines on the shade side of
objects should be used, except where they tend to thicken the work and
obscure letters of reference. The light is always supposed to come from
the upper left hand corner at an angle of 45 degrees.
5. The scale to which a drawing is made should be large enough to show
the mechanism without crowding. The number of sheets used must never be
more than is absolutely necessary.
[Illustration: Fig. 292.]
6. The different views should be consecutively numbered. Letters and
figures of reference must be carefully formed. They should, if possible,
measure at least one-eighth of an inch in height.
If the same part of an invention appears in more than one view of the
drawing it must always be represented by the same character.
7. The signature of the inventor is to be placed in the lower right-hand
corner of each sheet, and those of the witnesses at the lower left-hand
corner.
The title should be written with pencil on the back of the sheet.
Drawings should be rolled for transmission, never folded.
On page 235, fig. 292 exhibits a reproduction of a patent office
drawing, used in connection with specification papers in an application
for a United States patent.