3.1.1 Where
                                 calculations indicate the possibility of significant lateral vibration
                                 responses within the range of working speeds, measurements using an
                                 appropriate recognised technique may be required to be taken from
                                 the shafting system for the purpose of determining that hazardous
                                 whirling or excessive vibration does not occur.
                              
                              
                              
                            
                           
                           
                           
                              
                              
                              3.1.2 The
                                 method of measurement is to be appropriate to the machinery arrangement
                                 and the modes of vibration which are of concern. When measurements
                                 are required, detailed proposals are to be submitted in advance.