162. In this skeleton, the answers to the questions are in some cases printed, as "Who repair the tools?--Masters, Men"; in order that the proper answer may be underlined with a pencil. In filling up the answers which require numbers, some care should be taken: for instance, if the observer stands with his watch in his hand before a person heading a pin, the workman will almost certainly increase his speed, and the estimate will be too large. A much better average will result from enquiring what quantity is considered a fair day's work. When this cannot be ascertained, the number of operations performed in a given time may frequently be counted when the workman is quite unconscious that any person is observing him. Thus the sound made by the motion of a loom may enable the observer to count the number of strokes per minute, even though he is outside the building in which it is contained. M. Coulomb, who had great experience in making such observations, cautions those who may repeat his experiments against being deceived by such circumstances: 'Je prie' (says he) 'ceux qui voudront les repeter, s'ils n'ont pas le temps de mesurer les resultats apres plusiers jours d'un travail continu, d'observer les ouvriers a differentes reprises dans la journee, sans qu'ils sachent qu'ils sont observes. L'on ne peut trop avertir combien l'on risque de se tromper en calculant, soit la vitesse, soit le temps effectif du travail, d'apres une observation de quelques minutes.' Memoires de l'Institut. vol. II, p. 247. It frequently happens, that in a series of answers to such questions, there are some which, although given directly, may also be deduced by a short calculation from others that are given or known; and advantage should always be taken of these verifications, in order to confirm the accuracy of the statements; or, in case they are discordant, to correct the apparent anomalies. In putting lists of questions into the hands of a person undertaking to give information upon any subject, it is in some cases desirable to have an estimate of the soundness of his judgement. The questions can frequently be so shaped, that some of them may indirectly depend on others; and one or two may be inserted whose answers can be obtained by other methods: nor is this process without its advantages in enabling us to determine the value of our own judgement. The habit of forming an estimate of the magnitude of any object or the frequency of any occurrence, immediately previous to our applying to it measure or number, tends materially to fix the attention and to improve the judgement. Section II On the domestic and political economy of manufactures Chapter 13 Distinction Between Making and Manufacturing