- 3 - 603 



We tnus obtain a series of oictyres wnich are measureo so as to give the height attaineo Oy 

 tns sora/ at a series of known times, ana from these the initial velocity is obtained Oy analysis. 



It acoearea at the very outset that the soray carticlss were not oroceeOins with a 

 retnraatlon equal to gr^.vity, Out with si conslOeroDly greater rctaraatlon. The natural Inference 

 was that the soray oarticles were so small that consioeraole viscous resistance was in play. 



iccoraingly Insteaa of the equation of motion of the particles being 



where s is the height at time t, ana g is the acceleration of gravity. It Is assumefl that th 

 equation is 



-— t K — - - g 



ot^ at 



where k Is tne unknown viscous constant. 

 The solution is 



v^ being the initial velocity. 



Our measurements give a sarlcs of values of S at certain times. Tne initial time Is, 

 however, unknown, ana «e hnve to Jetfrmine three unknown quantities v^, v sna the inltUl time 

 from tne oossrvat Ions. 



Three observations are theoretically sufficient out to reouce casual error we take 6 points 

 ano combine in oairs s: as to got average values. 



A specimen recora is reoroaucco, olate 2. It sh;ws the exclcsion of a Toroeac War HcaS 

 500 lbs. of T.N.T. 



The f:n;wing is a cjcy ::f the mee.sureraents ana the analysis. 



I7tn September. 1919 . 



Toroeao war Heao 500 lbs. T.N.T. at aepth 50 feet 



in water lOO feet oeep. 

 Sistance between Blobs = 60 feet 

 On picture = 6.0 nm. 



Hence scale is 1 mn. = lo feet = 305 cms. 

 Tine scale 1 sscona = 120° 



Measureo neii^t of spray 

 at centre jn mms. 



1.3 



1.5 

 1.7 



From these observations Orawn on squared caper the following smoothea values are taken 

 as the basis of calculation 



1 S Calculatea ^y form'ila 



(1) tj .05 



(2) .05 .47 



(3) . 10 .83 

 W .15 1.16 1.16 



(S) .20 1.46 1.45 



.83 



