of  Animals  and  Vegetables . 25 
and  that  it  rauft  probably  have  been  lefs,  if  the  heat  of 
the  hen  had  not  been  fo  great. 
Finding  from  the  above  experiments,  that  fowls  were 
fome  degrees  warmer  than  that  clafs  commonly  called 
quadrupeds  (although  certainly  not  fo  perfect  animals) 
2 chofe  to  continue  the  experiments  upon  the  fame  prin- 
ciples, and  made  the  following  upon  thofe  of  a ftill  in- 
ferior order.  The  next  remove  from  the  fowl  are  thofe 
commonly  called  amphibious. 
exp.  xxvni.  I took  a healthy  viper,  and  introduced 
the  thermometer  into  its  ftomach  and  anus ; the  quick- 
hlver  rofe  from  58®  (the  heat  of  the  atmofphere  in 
which  it  was)  to  68°;  fo  that  in  a common  atmofphere 
it  is  io°  warmer. 
exp.  xxix.  The  viper  was  put  into  a pan,  and  the  pan 
into  a cold  mixture  of  about  1 o° ; after  being  there  about 
ten  minutes,  its  heat  was  reduced  to  37°.  It  was  al- 
lowed to  flay  ten  minutes  longer,  the  mixture  being  at 
1 3°,  and  its  heat  was  reduced  to  35°.  It  was  allowed 
to  ftay  ten  minutes  more,  the  mixture  at  20®,  its  heat  at 
31°,  and  it  did  not  become  lower;  its  tail  was  beginning 
to  freeze;  and  it  was  now  very  weak.  It  may  be  re- 
marked, that  it  became  cold  much  flower  than  many  of 
.the  following  animals. 
Vol.  LXVIII.  E 
The 
