CORE ORIENTATION 73 



The instrument can also be so constructed that the needle 

 is not freed by the relative displacement of the two tubes 

 Ri and Ri but by an improved water lead in which a valve 

 is closed under the pressure of a spring. The valve spring 

 is so adjusted that the valve stays open with the normal 

 rinsing current and will only shut on an increase in the speed 

 of the rinsing pump. 



The same objections apply in the main here as to the 

 apparatus of Gothan with respect to core fractures, etc. 



Lapp's Device. — This simple apparatus was invented in 

 1906 by Heinrich Lapp of the well-known firm of deep 

 borers in Ascherleben, Germany. The simple principle 

 shown in Figs. 38, and 39 has been adopted since in numer- 

 ous devices. Figure 38 shows a longitudinal section^ of 

 this core orientator with two horizontal sections below. 

 It consists of a cylinder a of suitable dimensions made in 

 two halves, the lower one fitting over the core in the hole. 

 Under the magnetic needle 6, which is borne on a spring 

 spindle bearing c, is a plate d of soft material. The needle 

 has a lower side pricker e. Above the needle on a rod i 

 is a plunger / carried through a shear pin h and having a 

 ring buffer g at its bottom end. 



On the rods being lowered and the bottom of the cylinder 

 fitting over the core stub, the plunger/ descends by its own 

 weight, or by the rod action, and buffer g presses the needle 

 down, making an imprint of e in the soft plate d and holding 

 the needle in its position of rest. The shearing pin h 

 prevents any turning and the lug k with the peg k' in the 

 housing a serves for correctly adjusting the housing in the 

 core tube. 



The device suffers from the usual defects of this type 

 of apparatus, i.e., cavings, poor cores in friable strata, 

 turning shocks, etc. Compare Hillmer's deviation and 

 dip measuring apparatus made by the same firm and dealt 

 with later on. 



Koemer's Core Orientation Apparatus. — This apparatus 

 was invented in 1907 by a German engineer, G. Koerner, 



1 German Patent No. 171,349, May 25, 1906. 



