872 SEC. 16. GEOLOGY AND MINING. 



3887a. Improved form of Air-meter for use in coal mines, 

 hospitals, &c. E. Cetti $ Co. 



3388. Patent Electric Velocimeter, for ascertaining the 

 velocity of air currents in any part of the workings of a coal mine 

 at a distance of two or more miles from it, in a chosen station 

 above ground. Francis Pastorelli. 



This consists of three parts : 



1. Four hollow hemispherical cups are fixed to the ends of four strong 

 metal arms (at fight angles) radiating from a central boss. At right angles 

 to it is attached the horizontal axis, which is mounted in a rectangular metal 

 box ; each revolution of the cups causes a contact to be made. 



2. The receiving instrument has a circular box with a dial mounted upon 

 a metal base ; it is worked by an electro-magnet ; by its means each revolution 

 of the cups is indicated, and motion given to a series of wheels. On the face 

 of the instrument are divided circles and indexes, which register from 10, 

 100, 1,000 and so on up to 10,000,000 feet. 



3. Attached to its side is a commutator, so that the current can be opened 

 or closed for timing or other purposes ; it is an ivory handle carrying an index, 

 which can be moved to point to off or on at pleasure ; it will also serve as 

 a means to prevent unnecessary exhaustion of the battery. 



4. A Leclanche battery of six No. 2 cells is connected with the above, so 

 that each revolution of the cups may be electrically transmitted and indicated 

 on the large circle of the receiving instrument which represents 10 feet of 

 velocity. The receiving instrument can be placed in any convenient position 

 above ground. The cup arrangement (Dr. Robinson's with mechanical modi- 

 fications) is intended to be used in the mine ; in the air-ways or workings 

 where the velocity of the air current is to be ascertained, its velocity is 

 registered on the dials of the receiving instrument. 



The inventor does not introduce this instrument with the idea that ex- 

 plosions will be prevented if it were generally adopted, but he has a strong 

 impression that, by its use under proper regulations, it will be the means of 

 diminishing them. 



3388b. Air Meter for testing ventilation in mines, hospitals, 

 and public buildings. L. Casclla. 



THEODOLITES, COMPASSES, &c. 



3390. Mining Compass, with independent vernier readings. 



Patrick Adic. 



339Oa. Casartelli's Improved Miners' Dial. 



Joseph Casartelli. 



The first improvement (1861) consisted in mounting the sight-plate on 

 axes cast on the compass-box, and attaching the arc for giving the angles of 

 inclination to one of the axes, with the index so fixed as to be moved by the 

 sight-plate when inclined to sight up or down the roads, and so give the angle 

 of inclination. The second improvement (1874) consists in substituting for 

 the arc a semi-circular limb fixed to the compass-box by pivots in the line N 

 and S in such manner as not to obstruct the view through the sights. The 

 degrees of angle are graduated on the face, and read off by indexes attached to 

 the sight-plate, which ride over the face of the semi-circle when the plate is 



