208 REPORT — 1855. 



either side of the instrument. The leg can either go into a joint of stone or brick- 

 work, or screw into a tree, timber, walking-stick, 8rc., according to tlie purpose for 

 ■whicli it is to be applied. It will answer well for the detail survej'ing in mines, 

 however contracted the working places may be. The surveys may be laid down on 

 paper without the aid of anything but a pencil, by first adjusting the north and south 

 line of the plan by the compass, and fastening the paper down by weights. The 

 compass then serves as the protractor, and by the scales the distances are measured 

 off. This method saves all calculation, ruling parallel lines, &c., and obviates some 

 instrumental errors. The thermometer needs no remark, but that it is useful in 

 examining ventilation. The Goniometer consists of an arm which can be raised up 

 against the lid of the box, and enables the eye to measure angles, crystals, cleavage, 

 &c. A magnifying glass is placed in one angle of the box, in the other is a tour- 

 maline for examining rocks at the bottom of pools, or along coast lines, &c. In the 

 bottom lid is a table of constants, suited for the objects of the different classes of 

 observers named. By turning back the elastic band, and lifting out the small arm 

 and sheet of mica, and adjusting the box by the spirit-level, a delicate anemometer 

 ■without friction is obtained, particularly useful in ascertaining the velocity of the ven- 

 tilation in the ends of mines. There are several other uses, too long to enumerate, 

 which will suggest themselves in practice. 



On an Application of Galvanic Power to Machinery. By Robert Mair. 



On a Screw-vent for turning Spiked Guns into use. By Dr. March. 



On Manoeuvring Steamers. By George Mills. 



Description of the Launch of the Steamer ' Persia.' By J. R. Napier, C.E. 



On a simple Boat Plug. By J. R. Napier, C.E. 



On a netv Method of Drying Timber, By J. R. Napier, C.E. 



On Practical Tables of the Latent Heat of Vapours. 

 By W. J. Macquorn Rankine, C.E., F.R.SS. L. & E. 



These tables give directly the latent heat of evaporation of one cubic foot of steam, 

 and of Eether-vapour respectively, at various temperatures and pressures of ebullition ; 

 such latent heat being given in foot-pounds by the formula 



(IP 



where P is the pressure and r the absolute temperature. 



On the Operation of the Patent Laws. 

 By W. J. Macquorn Rankine, C.E., F.R.SS. L. ^ E. 



While acknowledging the benefits derived from the amended patent law, the author 

 pointed out the following defects in its operation as subjects for discussion in the 

 Section: — 1. The granting of patents for useless inventions. 2. The granting of 

 more than one patent for the same invention during the currency of the provisional 

 protection of the first. 3. 'J'he granting of patents for foreign inventions to persons 

 other than the inventor or his assignee. How far these evils were to be removed by 

 improvements in the administration of the law, and how far by amendments in the 

 law itself, were subjects for further consideration. 



