|  | G |
SECTION G — PHYSICS

|  | G |
Note(s) In this section, the following term is used with the meaning indicated: "variable" (as a noun) means a feature or property (e.g., a dimension, a physical condition such as temperature, a quality such as density or colour) which, in respect of a particular entity (e.g., an object, a quantity of a substance, a beam of light) and at a particular instant, is capable of being measured; the variable may change, so that its numerical expression may assume different values at different times, in different conditions or in individual cases, but may be constant in respect of a particular entity in certain conditions or for practical purposes (e.g., the length of a bar may be regarded as constant for many purposes). Attention is drawn to the definitions of terms or expressions used, appearing in the notes of several of the classes in this section, in particular those of "measuring" in class Fulltext... Hierarchy... Expanded...G01 and "control" and "regulation" in class Fulltext... Hierarchy... Expanded...G05. Classification in this section may present more difficulty than in other sections, because the distinction between different fields of use rests to a considerable extent on differences in the intention of the user rather than on any constructional differences or differences in the manner of use, and because the subjects dealt with are often in effect systems or combinations, which have features or parts in common, rather than "things", which are readily distinguishable as a whole. For example, information (e.g., a set of figures) may be displayed for the purpose of education or advertising (Fulltext... Hierarchy... Expanded...G09), for enabling the result of a measurement to be known (Fulltext... Hierarchy... Expanded...G01), for signalling the information to a distant point or for giving information which has been signalled from a distant point (Fulltext... Hierarchy... Expanded...G08). The words used to describe the purpose depend on features that may be irrelevant to the form of the apparatus concerned, for example, such features as the desired effect on the person who sees the display, or whether the display is controlled from a remote point. Again, a device which responds to some change in a condition, e.g., in the pressure of a fluid, may be used, without modification of the device itself, to give information about the pressure (Fulltext... Hierarchy... Expanded...G01L) or about some other condition linked to the pressure (another subclass of class Fulltext... Hierarchy... Expanded...G01, e.g., Fulltext... Hierarchy... Expanded...G01K for temperature), to make a record of the pressure or of its occurrence (Fulltext... Hierarchy... Expanded...G07C), to give an alarm (Fulltext... Hierarchy... Expanded...G08B), or to control another apparatus (Fulltext... Hierarchy... Expanded...G05). The classification scheme is intended to enable things of a similar nature (as indicated above) to be classified together. It is therefore particularly necessary for the real nature of any technical subject to be decided before it can be properly classified.

INSTRUMENTS

|  | G04 |
HOROLOGY

|  | G04B |
MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME-PIECES USING THE POSITION OF THE SUN, MOON, OR STARS (spring- or weight-driven mechanisms in general Fulltext... Hierarchy... Expanded...F03G; electromechanical clocks or watches Fulltext... Hierarchy... Expanded...G04C; electromechanical clocks with attached or built-in means operating any device at preselected times or after predetermined time intervals Fulltext... Hierarchy... Expanded...G04C 23/00; clocks or watches with stop devices Fulltext... Hierarchy... Expanded...G04F 7/08)

|  | G04B |
Note(s) This subclass covers mechanically-driven calendar clocks or clockwork calendars, and the mechanical part of such clocks or calendars.

|  | G04B |
Subclass index
DRIVING MECHANISM | 1/00
WINDING |
Normal; automatic; combined | 3/00; 5/00; 7/00
Supervision; winding parts | 9/00; 11/00
CLOCK MOVEMENT |
Escapement; frequency stabiliser; setting frequency gearwork; adjusting thereof | 15/00; 17/00; 18/00; 13/00; 35/00
TIME INDICATING | 19/00, 21/00, 23/00, 25/00
TIME SETTING | 27/00
FRAMEWORKS; SUPPORTS; CALIBERS | 29/00; 31/00; 33/00
PROTECTION OF CLOCKWORK |
Cases; crystals, glasses; other protection means | 37/00; 39/00; 41/00, 43/00
UNUSUAL CLOCKS | 45/00, 47/00, 49/00

|  | G04C |
ELECTROMECHANICAL CLOCKS OR WATCHES (mechanical parts of clocks or watches in general Fulltext... Hierarchy... Expanded...G04B; electronic time-pieces with no moving parts, electronic circuitry for producing timing pulses Fulltext... Hierarchy... Expanded...G04G)

|  | G04C |
Note(s) This subclass covers electric features of mechanically-driven clocks or watches, such as electric winding of such clocks or the provision of electric contacts thereon.

|  | G04C |
Subclass index
ELECTRIC WINDING OF MECHANICAL CLOCKS | 1/00
ELECTROMECHANICAL CLOCK MOVEMENTS; ELECTRIC OR MAGNETIC ESCAPEMENTS | 3/00, 5/00
TIME INDICATING |
Optical; acoustical means | 17/00, 19/00; 21/00
TIME SETTING | 9/00
POWER SUPPLIES | 10/00
SYNCHRONISATION; MASTER-AND-SLAVE CLOCK SYSTEM; SYNCHRONOUS-MOTOR CLOCKS | 11/00; 13/00; 15/00
CLOCKS FOR OPERATING A DEVICE AT A PRESELECTED TIME | 23/00

|  | G04D |
APPARATUS OR TOOLS SPECIALLY DESIGNED FOR MAKING OR MAINTAINING CLOCKS OR WATCHES (machine tools in general Fulltext... Hierarchy... Expanded...B23, Fulltext... Hierarchy... Expanded...B24; hand tools in general Fulltext... Hierarchy... Expanded...B25)

|  | G04D |
Subclass index
HAND AND MACHINE TOOLS | 1/00, 3/00
LUBRICATING DEVICES | 5/00
MEASURING AND TESTING APPARATUS | 7/00
DEMAGNETISING DEVICES | 9/00

|  | G04F |
TIME-INTERVAL MEASURING (measuring pulse characteristics Fulltext... Hierarchy... Expanded...G01R, e.g. Fulltext... Hierarchy... Expanded...G01R 29/02; in radar or like systems Fulltext... Hierarchy... Expanded...G01S; masers Fulltext... Hierarchy... Expanded...H01S 1/00; generation of oscillations Fulltext... Hierarchy... Expanded...H03B; generation or counting of pulses, frequency dividing Fulltext... Hierarchy... Expanded...H03K; analogue/digital conversion in general Fulltext... Hierarchy... Expanded...H03M 1/00) [2]

|  | G04F |
Note(s) This subclass covers: apparatus for measuring-off predetermined time intervals; [2] apparatus for producing such intervals as timing standards, e.g. metronomes; [2] apparatus for measuring unknown intervals, e.g. precision systems for short-time-interval measurement. [2]

|  | G04F |
Subclass index
MEASURING PREDETERMINED TIME INTERVALS |
Producing time standards | 5/00
Apparatus: without driving mechanisms; with driving mechanisms | 1/00; 3/00
MEASURING UNKNOWN TIME INTERVALS |
Mechanically; electromechanically; electrically; otherwise | 7/00; 8/00; 10/00; 13/00

|  | G04G |
ELECTRONIC TIME-PIECES [3]

|  | G04G |
Note(s) This subclass covers: electronic time-pieces with no moving parts; [3] electronic circuitry for producing timing pulses irrespective of the nature of the time-indicating means utilised. [3] This subclass does not cover electronic time-pieces with moving parts, which are covered by subclass Fulltext... Hierarchy... Expanded...G04C. [3]

|  | G04G |
Subclass index
PRODUCING TIMING PULSES | 3/00
TIME-SETTING; SYNCHRONISING | 5/00; 7/00
TIME- OR DATE-INDICATING |
Visual; optical signals; acoustic signals | 9/00; 11/00; 13/00
OPERATING A DEVICE AT PRESELECTED TIMES | 15/00
OTHER SUBJECTS | 1/00