292 



FARMERS' REGISTER. 



[No 5 



themselves, ihun thoy could be in their own labo- 

 mtory?— Certainly; it" a principle is established, 

 it resis as a matter of mechanical detail, or oi 

 mechanic d situation and position, to know whe- 

 ther it can or cannot he applied, practically, with 

 advantaijp. Sir Gcoro-e Capley inlbrms me that 

 he used the nrinci|)le of reflection to throw day- 

 liijhi to sonie men who were working; a deep well. 

 It'^had a beantifuleflect, and answered the purpose 

 perfectly. His reflector was nothinji: more than a 

 piece of tin plate. The daylight is not sufficient- 

 iv intense; we cannot iiicus it so as to be passed 

 through the galleries of mines. 



In your oi;inion, would the experiment be bet- 

 ter conducted by placing the liglit above the shaft, 

 or at the bottom of lhe"shaft?^It would depend 

 on the depth and .«?ize of the shaft. 



Assume 200 yards in depth? — In such case 

 above; you get at the materials and apparatus for 

 forming the light better; the distance of 200 yards 

 has very little effect in diminishing the light; re- 

 flected light does not obey the same laws as radia- 

 ted light ; radiated light diminishes as the squares 

 of the distances, but reflected light does not; this is 

 contrary to received opinions, but [ am satisfied it 

 is correct, from the observations I have lately made. 



You have not supposed any difficulties in the 

 application of this light, beyond those already 

 stated, which the committee understand to be the 

 interruptions occasioned by stoppings or trap-doors 

 in the mines, or the extreme sub-division of the 

 reflected light? — I have: there are othens, but I 

 think of minor importance, which can only be 

 justlj' appreciated in practice. 



The shafts of the mines are placed at right an- 

 gles, that is, they are driven along, and they begin 

 at the furthor end, and then work upwards; is 

 there any ditficuliyin transmitting the light at right 

 angles? — Not any dilTiculty whatever; you may 

 transmit the light in any angle you please; it may 

 first be thrown down a shaft, and then sent into 

 any angle, upwards or downwards, or on one side 

 or on ano'her. 



Suppose there be a space of two or three feet 

 left on one side, or on both sides, of the carriaores 

 conveying the minerals along the galleries, the 

 light might be transmitted independently of the 

 s])ace occupied by the carriages? — Certainly. 



Or through a similar space above the cariiages? 

 — Yes. 



And you propose to obviate the difficulty of 

 passing through the trap-doors, that means in the 

 mines, by the insertion of glass in those doors; 

 Avhat is the smallest size you would consider suf- 

 ficient lor that purpose? — It would depend upon 

 the situation in which the door was placed in the 

 mine; If in the first gallery, where you wanted 

 the fiiU stream or supply of light to pass, you 

 would require twenty inches diameter; when doors 

 occur further on, in the division of light, perhaps, 

 three or lour inches in diameter would be suffi- 

 cient. 



Would that be sufficient to light a gallery at the 

 distance beyond the door many hundred yards, if 

 twelve feet wide? — Certainly. There is another 

 valuable natural fact that I would mention here: 

 the stream of light, as it passes through the air, is 

 refhtcted by the atmosphere, and thrown in all di- 

 rections several yards, wiih an intensity sufficient 

 for practical purposes. JMy house at Biule has a 

 long gallery in it; I passed a stream of reflected 



light through thai gallery; every bed-rooni enter- 

 ing into the gallery was sufficiently illuminated in 

 every part for a person to pick up a pin. The 

 light in the bed-rooms was refi'acted light, from 

 the reflected light passing through the gallery. I 

 conceive that unless men are working at some dis- 

 tance fiom the stream of light through a gallery, 

 a reflector would be scarcely necessary for them. 

 Dust, floating in the atmosphere, reflects a good 

 deal of light sideways. 



Would the accumulation of dust upon glass so 

 inserted in one of the trap-doors, be a serious im- 

 pediment to the light? — Not practically, because 

 it could be easily wiped away. 



Are you aware that a boy is generally stationed 

 to take charge of those doors? — Yes. 



And of course, he might have instructions to 

 keep the glass perfectly clean! — Certainly. 



KXTRACTS FROM THE REPORT OF PROFESSOR 

 DUCATEl's survey of MARYLAND. 



Geological Examination of Dorchester, Somerset, 

 and fForcester Counties, on the Eastern Shore 

 of Maryland. 



These three counties, comprising more than 

 one-tbird of the territory of Maryland, east of the 

 Chesapeake bay, though presenting but little va- 

 riety in their mineralogical and geological fea- 

 tures, are yet not devoid of interest in ^hese res- 

 pects, while in others they ofler subjects of consid- 

 eration of the deepest importance to the prosperity 

 of the state. 



The most prominent geological feature in this 

 district is a successon of sandy hillocks, in what 

 are termed the upper portions of these counties, 

 being a continuation of the ridge dividing the 

 courses of the waters that empty themselves to 

 the east into the bay of Delaware, and to the west 

 into the Chesapeake. These hills of sand are 

 themselves arranged in ridges, running generally 

 north-east and south-west, diminishing in eleva- 

 tion towards the southern extremity of the penin- 

 sula, forming a curve on its eastern boundary, and 

 presenting every appearence of a series of sandy 

 beaches produced by successive retreats of an 

 ocean. No organic remains of any kind are 

 known to have been found within this portion of 

 our territory, excepting a deposite of oyster shells 

 at the head of Taylor's Creek, two miles above 

 the fork of the Nanticoke, and ten miles below the 

 Ibssililerous deposite occurring on the north-west 

 branch of this river, and previously referred to as the 

 newer pliocene formation. This deposite is over- 

 laid by soil six feet in depth. The shells contained 

 in it are much in the same condition as those oc- 

 curring in the accumulations supposed to have 

 been made by the aboriginal inhabitants of the 

 country ; /. e. the valves are separated, and are 

 not, so far as perceived, associated with any other 

 marine shells. They are, however, perforated and 

 covered with serpulm. as if fhey had lain long, 

 after the death of their inhabitants, at the bottom 

 of the sea. But they are at a great distance from 

 any actual oyster beds, and are in a more advanced 

 state of disintegration than the fossil 03'sters here- 

 tolbre observed; whilst, on the other hand, thfcy 

 are covered, as aforesaid, by a thick stratum of 

 sand, no where else remarked to overlie Indian 

 banks. 



