1884.] future of naval warfare. 219 



(even when above water in cruising), a distance of 2^ miles from 

 an ironclad can easily be approached without the smallest danger. 

 The boat then being submerged and a "full head" of steam "put 

 on," the ironclad can be reached in some 15 minutes; and when 

 within some few yards, a percussion shell is fired against the 

 bottom of the utterly helpless and harmless ship. Now it is 

 known that the most powerful pumps in the navy cannot keep the 

 water down when it pours through a 20-inch (diameter) hole : hence 

 the possibility of preventing a vessel from sinking which has an 

 aperture of several square yards torn in her bottom by the explo- 

 sion of a shell does not exist. Men, guns, stores, all — must sink. 

 ****** 



Such in brief, are the functions of the boat one kind of which 

 was exhibited; and in leaving the subject I have only to add that 

 the boat exhibited was not furnished with guns and armour, but 

 both of which it was my design to have furnished it with (could I 

 have managed to do so) before it was exhibited. 



Class (6). Boats of this class are in like manner intended to 

 transport men and the material of war beneath the sea. They are 

 not intended for speed : but for carrying troops under water for 

 short distances, as across the British Channel, which thus becomes 

 one of the most dangerous frontiers to defend that a state can well 

 possess. However, as no boats of this kind were exhibited, 

 nothing more will be said of them here. 



Class (c). As this class was only represented by a very poor 

 model, half made [and badly constructed], I will only say that the 

 motor here is electricity, and the boats are to be fitted with 

 torpedoes and used in connection with fast cruisers. 



With this I finish this brief abstract of my paper. 



(5) Note on a peculiar sense organ in Scutigera coleoptrata, one of 

 the Myriapoda. By F. G. Heathcote, B.A., Trin. Coll., Cambridge. 



The organ is situated on the ventral surface of the head at a 

 short distance from the mouth, near the base of the mandibles. 

 A slit-like opening in the ventral median line, between the maxillae 

 and the base of the mandibles, leads into a sac lined with chitin. 

 This sac is of elongated pear-like form, its longest diameter being 

 parallel to the ventral surface of the head. Two longitudinal folds 

 in its dorsal roof project close together into the body of the sac, 

 partially dividing it into two pouches with a deep narrow median 

 recess between them. In the anterior region of the sac a lateral 

 fold on each side of the sac projects parallel to the ventral surface 

 of the head, thus forming a deep lateral recess on each side. 



The effect of these lateral and median recesses is to form a free 

 lip on the dorsal median and lateral ventral aspects of the pouches. 



The surface of the sac, except at the folds and in the recesses 



