Neglect of duty is the omission to perform a duty. Neglect of duty has reference to the neglect or failure on the part of a public officer to do and perform some duty or duties laid on him as such by virtue of his office or which is required of him by law. It is not material whether the neglect is willful, through malice, ignorance or oversight, when such neglect is grave and the frequency of it is such as to endanger or threaten the public welfare, it is gross. [State ex rel. Hardie v. Coleman, 115 Fla. 119 (Fla. 1934)].