The editor hopes that Officers detecting any errors, which must necessarily be numerous in the first issue of a work of this character, or who have any alterations or additions to propose, which may appear to them to be likely to add to its general usefulness, will unhesitatingly notify the same to the Secretary R.E. Institue, Chatham, since it is only by the combined efforts of those whose particular tastes or oppirtunies have led them to collect information on special subjects, that the R.E. Aide Memoire can become of real value to the Corps at large, and the information it contains be kept fairly up to date. Several subjects, such as the important one of electricity, as applied to lighting, telegraphy, and firing explosives, &tc., have had to stand over fror the present, in order not to delay the issue of this volume.

H.C. Sheddon, Lieut.-Col. R.R., Chatham, November 1883