Popular Science Monthly 



903 



A Strange Spongelike Rock 



THE so-called sponge rocks near 

 Livingston, Montana, have at- 

 tracted the attention of many travelers 

 and scientists on account of their re- 

 markable tracery and porosity. They 

 appear like huge pieces of pumice stone 

 intricately carved by Nature into in- 

 numerable cells, webs and cavelets. 

 Some of the pieces are almost threadlike. 



The rock is sandstone, which was 

 formed millions and millions of years 

 ago when the entire State of Montana 

 was the bottom of a sea. In the course 

 of ages, Montana has been bodily up- 

 lifted several thousand feet. 



The spongelike formation of the rock, 

 as it appears to-day, is of course due to 

 the wearing action of water and wind, 

 the softer particles of the rock having 

 been washed or blown away, leaving the 

 harder portions standing. There are a 

 number of these rocks in the same 

 locality, and several of them are said 

 to have been appropriated by wild bees 

 and other insects. 



The spongelike appearance of this rock is 

 due to the wearing action of wind and rain 



Take this portable dark-room with you in the 

 woods and develop your negatives on the spot 



A Portable Dark-Room for 

 Photographers 



A PORTABLE dark-cabinet has been 

 invented, which does away with 

 many inconveniences encountered by 

 photographers in developing their nega- 

 tives without the advantage of a suita- 

 ble dark-room. A metal framework 

 supports a table or shelf adjustable to 

 any desired height. Extending above 

 the table are two rods supporting a 

 square frame to which is attached a large 

 hood. This hood completely envelops 

 the table and affords enough room for 

 the upper portion of the photographer's 

 body behind the table. A hole in one 

 side of the covering is used for intro- 

 ducing the materials in the cabinet. 

 Another hole in its lower part is provided 

 with a strap or elastic band, which 

 passes around the waist of the operator 

 as he enters the hood. 



The cabinet is lighted by a window of 

 ruby glass directly over the table and 

 opposite the photographer. Eresh air 

 is supplied by means of a mask with a 

 rubber tube leading to the outside. 

 Tourists who take many pictures can 

 make'good use of this cabinet. 



