36. Don’t fail to keep yourself neat and tidy.
37. Don’t fail to be polite as well as neat and brave.
38. Don’t fail to keep the tubes clear and free from soot and ashes.
39. Don’t let too many ashes gather in the ash-pit.
40. Don’t disturb the fire when it is burning good nor stir it up too often.
41. Don’t be afraid to get instruction from books and engineering papers.
42. Don’t fail to make an honest self-examination as to points upon which you may be ignorant, and really need to know in order to properly attend to your duties.
43. Don’t allow too much smoke to issue from the top of the chimney if the cause lies within your power to prevent it.
44. Don’t think that after working at firing and its kindred duties for a year or two that the whole subject of engineering has been learned.
45. Don’t forget that one of the best helps in getting forward is the possession of a vigorous and well-balanced mind and body—this covers temperance and kindred virtues and a willingness to acquire and impart knowledge.