The Montgomery advertiser., 1904-11-13
A MECHANICAL MARVEL.
Cam Rowiand's Famous Apparatus be
 Equaleds

Equaleds
 Baltimore Special to The New York
 Tribune.
 The scientific world is interested In an important mechanical operation at the physical laboratory of Johns Hop kins University. Should the work De A failure there will be some serious inconvenience to the various fields of science In which spectroscopy plays an important part.
 The successful conclusion to the operation will be the answer to ques- tion frequently advanced since the death of Professor Henry A. Rowland whether the secret of cutting the thread for the playground screw upon which the manufacture of the famous Rowland spectroscopic gratings depends has been lost. Since Professor Rowlands's death there has been a de- cided disinclination on the part of the physical faculty to talk about the mat ter, and many persons conceived the idea that the secret of cutting the deli cate screw had passed away with the death of the great scientist and mathe- matician.
 Now, under the direction of Lewis E. Jewell, assistant in practical photog- raphy and spectroscopy In Johns Hop kins University. and with the trained hands of Foreman Charles Childs, of the Mechanical Department, the first new screw since the death of Professor Rowland is to be cut. and, if successful, the new machine Is to be added to the three other machines in the equal-tem-. perature vault of the physical labora- tory.
 The question as to whether the mak- ing of the screw is secret or not Is an iy,ta the dnIhf CnnrPrninU which has been deepened by the in- evitable process of circumstances which came about three years ago.
 Professor Rowland, who was of an extremely fine mechanical turn of mind as well as mathematician. devised a method of cutting the screw and grind ing it under water which he taught to his head mechanic. Theodore C. Schneider, and the latter became ex- ceedingly proficient in making the theads and the ruling machines, and then in cutting the graftings. The de- partment, while not refusing informa tion to other universities. managed to keep the secret of cutting the screw within it's own walls.
 For years. then, the grating machines in the Hopkins physical laboratory ground away in monotonous regularity, their fine diamond points slowly but surely cutting their thousands of lines to the inch upon polished plates of steel or glass.
 And then Schneider died. In one month-apparently before a new phy- sicist could be trained to direct the work-Professor Rowland passed away suddenly. and even Professor Remsen was inclined to believe that the secret of making the valuable grating screws had passed away with the scientist. Had this been so, the three grating machines in the Hopkins vaults would have been absolutely priceless.
 Since then there has been speculation pro and con as to the likelihood of the successful cutting of a screw by any of those who survived the great man and Schneider.
 After Schneider's death Charles Childs. who had long been associated with the mechanical work of the labo- ratory, was entered under Professor Rowland's instruction. and with the knowledge gained in this short time. and with working under a skilled scientist now. there Is felt to be little doubt that he will succeed
 The principal point in making the screws Is grinding it under water. The screw must be very accurate, as there are many thousands of lines cut upon the plate within the space of an inch. and the screw must be very finely ad- justed in order to shift the diamond point small fraction of an mich at each revolution. The gratIngs are of great value in spectroscopy and chemistry. and their loss would be irretrievable to the scientific world.
 The significance of the approaching test lies in the fact that for certain classes of spectroscopic work a pratine is preferable to an instrument composed of prisms. grating is a concave mirror, on whose surface fine parallel