Nkwalite mmepe teknụzụ akara agba nke mbụ

N'agbata 1926 na 1933, onye Danish mepụtara na onye na-emepụta igwe NielsA Christensen zụlitere ma tinye ụdị okirikiri a.E bipụtara usoro ya (O-ring) na 1930, na 1933, ma nweta nnukwu ihe nrite na 1938.