Trans. Roy. Dubl. Soe., Ser. IT., Vol. VIT. Piatt XX XIY. 
Py 1 ) Sas 1¢ yy ay a 7 
Fig, 6,.—Scale and View photographed through instrument 
shown in Fig. 5. 
Fic. 7.—Staff. Cross, Scale, and Level Bubble, photographed 
through instrument shown in Fig. 8. 
t= 
Fic. 8.—Photograph of Hand Level in use. Fic. 9. —Photograph of Prismatic Compass in use. 
M‘Farlane & Erskine, Edinr. 
